All of the guides I could find were for the Steam version of the game. I never see any error messages or crashes, the game just starts up with no mods present no matter what I do.
I have tried to follow numerous online guides, but none of them helped. It might be important to know that I got it from GOG, not Steam. I want to use mods with it, but can't get a single one to work. I just performed a clean install of Fallout 3 GOTY edition (version 1.7.0.3) on Win10.