The fdroid repos can get kinda outdated. But in my personal experience, the app has shown no issues. I guess being compliant with the tirrent protocols is all that matters for it to work.
There isnt much to say about how to use it. Just install the app, search for a torrent you want to download (be it via a magnet link, or a .torrent file) and thats it.
LMDE. Not Ubuntu based, but Debian based so its the closest I can think on the top of my head. It got 32 bit support and Cinnamon desktop.