This is a guide that someone on Reddit wrote and it helped me a lot. It looks complicated with the first glance, but when you do the steps it takes less than 15 minutes. I changed the order of the original slightly and added a few infos to make it easier:

"Guide installing Stremio with Torrentio and Real Debird on your desktop.

Stremio

Go to https://www.stremio.com/ Download the relevant client for your platform (Windows/Mac/Linux) Open Stremio and sign up with email or facebook

Real Debird

Go to https://real-debrid.com/ Sign up Go to Premium Offers ($3 for one month, $16 for 6 months) Choose a package and subscribe

Torrentio

Go to https://torrentio.strem.fun/configure Choose your options for providers, quality, foreign language etc You can now choose to install Torrentio without a Debid Provider. Personally I use Real Debrid to connect directly to a server vs having my IP shared in peer to peer and to speed up performance. Torrentio has a slot for a possible API key (the Real Debrid key) To install with Real Debrid follow the next steps: Go to the API key with this link: https://real-debrid.com/apitoken Copy the API Key and go back to Torrentio and paste it under RealDebird API Key Install

Stremio with Torrentio installed

Check the addon installed correctly Click the puzzle piece up on the top right that says 'Show All Addons' Click My Addons and scroll until you see Torrentio Test stream a movie or TV show Go to Discover Click on a Movie or TV show and click 'Show' You should now see [RB+] Torrentio - Quality Enjoy streaming"