When I try to log in to do anything with a game on my computer, all I get is a mesage "opps, something went wrong, click below to log into GOG Galaxy...with a Log In box. And all it does is keep giving me the same error all the time, so I cannot oplay or install any games.

the online servers have been wonky for weeks why have galaxy client and such when they don't install your games. So you'll have to do it manually because their junk isn't working.

I did this, but no matter what it tries to log into the app and cant.

Amazon Prime Gaming has Fallout New Vegas for free right now, I downloaded it,...and it automatically runs through the GOG app....and cannot.

First off, ignore the big blue button and expand the offline installers section.

If you did install using the actual offline installers, then ignore the Start Menu or desktop shortcut. Go right to the game installation folder. The premade shortcut you find there should launch the game instead of GOG Galaxy, or you can just launch the executable directly or create your own shortcut.