In case you haven’t realized, the user and pass in the docker compose are for setting the user/pass that you will enter on windows to access the share. It doesn’t have to be the same as the Linux server user account - though mine is the same because it’s easier to remember.
After I check the usual torrent sites, if I can’t find it on Usenet then I try finding random sketchy streaming sites (just by duckduckgoing title + year + stream) because usually you can youtube-dl them with a little fiddling, then my last resort is a DHT indexer like btdig. That’s more risk with viruses but if you’re paying attention it’s not that hard to avoid, but DHT indexes have lots of ancient stuff so be prepared to wait for seeds if you find it.
Sometimes I also find what I’m looking for on like page 7 of duckduckgo results at archive.org
Edit: also check soulseek - it’s primarily for music but you can share any file. I share my entire movies collection and get a constant stream of people downloading from me daily so it seems people search for and seem to also share TV and movies so it’s worth a check.