I really liked the concept of this and had high expectation, but I just tried this out following their documentation and not a fan so I'll have to pass / find a better alternative if one exists.
The docker-compose.yml given seems to cause the containers to be lacking permissions to save images and even the DB: logs show images can't be created/saved, restarting the container wipes the DB. No files created at all on the mounted volumes paths. The volume for game files works great though so that's confusing. I can probably troubleshoot that but this is the first container I've ever had such an issue with so I won't bother particularly due to the next points:
On the app itself I was pretty disappointed that it doesn't at the very least extract the files for you, and won't even skip all the manual junk for direct play games that I took the time to name properly with (DP) on the archive files. The reason given is there may be too many manual steps/variations for installation but direct plays don't need any of that.
Given the manual steps required I'll stick to copy/pasting the files off my server to my local games folder, the games themselves being added to steam if I really need to go that far with them.
I had forgotten that you could pay them.