This link explains things fairly quickly for all debrid, the service I use is real debrid which you can follow identical steps for setting up: https://www.desidime.com/discussions/use-stremio-debrid-all-debrid-real-debrid-for-watching-content#:~:text=Debrid services are basically torrent,and windows%2C and works seamlessly.
The idea is essentially debrid services download the content of a torrent, and once one user has requested them, its stored and available for all other users to download, so no more dealing with Torrents with 0 seeders, at the speed of top grade file hosting services. You could use it for downloading content quicker and storing it on your local drives.
Oh god it feels good to be back.