No luck getting my Lemmy instance up and running, is this a good place to get some help?

I'm not exactly a linux beginner but I'm far from an expert and I could use some pointers. I have a domain and a VPS through Namecheap, I chose Ubuntu 20.04 LAMP and I've tried several guides to get this working but something always goes wrong sooner or later.

My latest attempt is to follow along with this guide: https://join-lemmy.org/docs/administration/install_docker.html

No errors until the docker-compose up -d command, then

ERROR: yaml.constructor.ConstructorError: while constructing a mapping in "./docker-compose.yml", line 26, column 12 found unhashable key in "./docker-compose.yml", line 26, column 13

which leads to image: {{ lemmy_docker_image }}

I guess I could start over with a different guide but I'm just chasing my tail at this point. Could any kind soul suggest where to go from here?