Lemmy on Docker - Postgre Authentication Fail

I'm trying to get Lemmy up and running on an Ubuntu 22.04 host. I've followed this guide supplemented by googling.

I can actually get to the front end, but it gives me "There was an error on the server." When I dig into the logs, I see this:

"thread 'main' panicked at 'Error connecting to postgres://lemmy:<my pg password>@postgres:5432/lemmy: FATAL:  password authentication failed for user \"lemmy\"\n","stream":"stderr","time":"2023-06-26T03:14:17.47460915Z"}

The only thing I can find about this error related to Lemmy is this thread, which indicates that the password was not defined in the docker-compose.yml file prior to starting the containers. I have since redone the configuration three times, each time deleting the volumes folder and double-checking that my postgre password is correct both in docker-compose.yml and lemmy.hjson.

Any ideas what might be the problem? Thank you kindly for any help you can provide!