Honestly, for those tools, I'd recommend posting in piracy@lemmy.dbzer0.com.
Echoing some other comments, those are decently complex tools all around. I'd recommend doing a few tutorials on docker before trying out that project (short ones, just to build a mental model).
As others have said, docker is a command line tool. docker -v in your terminal should be enough to "find" it. That'll show you the version of docker you have installed.
From there, I'd recommend the hello world image to start (this should get you there https://www.geeksforgeeks.org/docker-hello-world/).
From there, keep messing with it. Get more familiar with docker through their docs. Read a bit on images vs containers, port mapping, and volumes and mounts.
As others have said, look for docker only in the terminal. And then expect to spend a little time familiarizing yourself with what problem docker solves and how it solves it. Once you've got docker in your back pocket, you'll be very well situated to set up all kinds of apps.
And when you run into other problems, there's communities to answer and work through the issues
Huge respect for what you've built here, but it might be worth reaching out to the lemm.ee admin. I only know enough DevOps and cloud hosting to be dangerous, not helpful. But his instance seems stable and scalable. He might be able to offer some insight into the issues here