I can't find the solution to this anywhere. I just installed gog galaxy version 1.2.51 and right now my library is empty. I want to add all my steam games and non-steam games to it but I cannot figure out how to. I had read that "scan and import folders" is one way. Doesn't recognize any of my 50+ games. I have also read that manually importing the game folder itself is the way to go, except I have no option to important.

The last topic I read up on this was back from 2015 where the version was older. Anyone know how I can accomplish this now? There must be something extremely obvious I am missing.

PS: I reinstalled one of my steam games AFTER I downloaded Gog Galaxy and that did not work so please don't suggest that.

Congratulations, you've misread the cards.

The Scan and Import feature is only for GOG Games and GOG games alone. You can't tell GOG to look for your Roms, your Steam Games, and your hatless Hatris from Humble.

You can import non-gog games, just you need to create custom .ini file.
Just copy file from other installed gog game and edit values like paths, titles, etc and type fake ID of game, and finally, try to import folder again.