I'm not from the US, either. But from what i understand, the issues comes from the US having a "first past the post" voting system on a state level.
The President is not elected by the percentage of votes, but each of the 50 states gets assigned a number of electors, based on their population. When a party/candidate has won the majority of votes within a state, they will receive all the electoral votes of that state.
Here's a simplified example of how that works: Let's assume 3 states with an equal ammount of inhabitants (let pop=1 million) and an equal ammount of electoral votes (let el=10)
State 1 has:
600.000 votes for candidate A (60%)
400.000 votes for candidate B (40%)
State 2 has:
200.000 votes for candidate A (20%)
800.000 votes for candidate B (80%)
State 3 has:
510.000 votes for candidate A (51%)
490.000 votes for candidate B (49%)
candidate A has received a total of 1.310.000 votes (~44%)
candidate B has received a total of 1.690.000 votes (~56%)
candidate B has won the popular vote, because most people voted for them.
However, candidate A won the majority in States 1 and 3. So candidate A will receive all 20 electoral votes of those states (which they won by only a comparitively small margin), whereas candidate B will receive only 10 from State 2 (which they won by a landslide).
As a result, candidate A will become the next president.
And the number of electoral votes hasn’t been updated in forever, so they aren’t really proportional to the state’s population anymore. California, for example, should have more votes than it currently does.
That is how it works, also electoral votes for each state are not scaled to the population of that state which means low population (often red) states get a disproportionate influence on national elections
That's it, with the added problem that those electors aren't really evenly matched to population. Each state is guaranteed at least 3 electors, with more being added proportional to population. This means the states with the least population get the most electors per vote, and also tend to be pretty consistent and homogenous in who they vote for
The U.S. was founded by slavers, and in order to preserve the rights of white men to own slaves, they built several anti-democratic institutions into the constitution of the new country. Northern states had fewer slaves and more voters, while southern states has more people but most of them weren't allowed to vote. A one-person one-vote system that included slaves would result in the end of slavery. A one-person one-vote system that excluded slaves would give most of the political power to the north, and would probably end slavery. So to make sure people could continue to be deprived of their humanity, the electoral college was invented.
All states were given votes in the college proportional to their population, with slaves counting as 3/5 of a person. This gave greater power to the plantation owning whites who were responsible for ratifying the constitution, and insured nothing short of a civil war could end their reign of terror.
After the civil war the electoral college remained, and continues to distort the popular vote.
This graph supposes "did not vote, as in people who could have cast a ballot but did not for whatever reason" is a candidate, which they aren't. This is to point out that the plurality of Americans don't vote.
We have this thing a bunch of morons invented 200 years ago called the Electoral College which is stupid and dumb and bad.
Each state gives a certain number of points, and if you win the state you win all the points from that state, candidate with the most points wins. So if 51% of people in a state vote for a candidate, that's exactly the same number of points as if 100% vote for them. That means that if one candidate wins a lot of states but not by much, and the other candidate wins other states by a landslide and overall gets more votes, maybe the first candidate still wins because half those votes don't count for anything, what matters is the points.
Also, technically each state has its own mini government that gets to decide who to give the points to, they don't have to let people vote. That's how there is a conspiracy called the "Interstate Compact" various states have agreed to, where if enough states agree then they will just give all the points to the candidate with the popular vote nationally, rather than giving the points to the candidate the people of that state voted for. The idea being to get rid of the points system and make it so the winner of the popular vote always wins.
edit: Looked it up and noticed that what I said about 51% giving all points isn't actually universally true, due to the state government getting to decide how the points are allocated and some of them doing it differently:
All states except Maine and Nebraska use a party block voting, or general ticket method, to choose their electors, meaning all their electors go to one winning ticket. Maine and Nebraska choose one elector per congressional district and 2 electors for the ticket with the highest statewide vote.
I'm not from the US either, but I've seen enough to attempt answering this.
They have two voting systems
popular vote
electoral college vote
Popular vote is the easily corruptible people going out and voting after a long period of politicians lying their teeth off face to face.
Electoral college vote is a bunch of easily corruptible fuckwits who vote with whoever pays best, regardless of popular voting.
Electoral college vote seems to matter more than popular vote. Not sure how or why. So less popular candidates can win because fuck the people, I guess.
Alright, the system is bad and problematic, but it's not quite that bad and problematic.
While it's theoretically possible you could subvert an elector by bribing them or whatever, there are systems in place to prevent that, and they haven't really needed to be tested. The closest we've come to that problem wasn't electors being bribed, it was Donald Trump bringing people who weren't duly appointed electors to the capitol to try and let them cast votes instead. So not bribing electors, but replacing them. Still the electoral college has a lot of issues and is pretty much obsolete even for the most charitable interpretation of its purpose
As for the popular vote being "corruptible" people voting, I don't know what the qualifier is trying to accomplish. Why "corruptible"? The "did not vote" people are folks who are convinced their vote won't matter, as well as folks for whom voting has been made deliberately "challenging" (read: effectively impossible). The people who do vote generally feel like they made the right decision, in my experience, win or lose, even if they decide to vote differently in the next one.