Fresh Install Cannot Connect "Failed API"

[F1zzyD]

I just put together the compose.yaml and extra things from the official guide. However, when I go to localhost:8080 the webpage says "Cannot get file" and the logs say something about "Unknown API". I'm not sure how I'm getting this error when I copied and pasted everything from the guide. All the permissions look good as well. The only thing I did change was the ports reading 8080:8080 to 8181:8080 as I already have a container running on 8080.

What's the problem here?