You'll likely also need to pay for a Debrid service. It's basically a download caching server, so if one user downloads a file, it's available to everyone.
With Stremio, that means that popular media will already have a zillion options pre-cached. If you want more niche stuff, then you can do the extra step to get your Debrid service to download it for you (assuming there's a public teacher that has it with seeders.)
It should also work for those download/file sharing sites, but I haven't bothered to figure it out yet.