Fallout 3 (GFWL) - Fallout 3 Epic games?

No. This PC version with achievements is the old Games for Windows Live version. Previously, the Steam version had the GFWL client attached to it, but it was removed in a patch. Earlier this year I was in the same spot as you, so this is how I got it to work after Steam removed GFWL.

First, I bought the disc version of Fallout 3 PC on Amazon (It should say "Games for Windows Live" at the top of the box art) for real cheap. Just took a quick glance and it's going for 7 USD on Amazon.

Secondly, you will need to download the latest version of the GFWL client. Here is a thread with links needed (I got mine from just googling around so If this doesn't help you can try that) GFWL - How do I unlock achievements when playing a physical copy of a game?

Finally, install the game via disc on the PC with the GFWL client. Sign in, start the game, and you should be connected to the GFWL servers and able to earn achievements. Don't worry if you can't access the GFWL marketplace, they shut that down years ago so people can't buy stuff from it.

Couple of notes. I could not for the life of me get this to work on Windows 11. I tried and tried, but nothing. I ended up taking the disc when I visited my mom and doing it on her computer as she still had Windows 10 lmao. But hey it worked. You only need to get to the menu anyway to type in the console commands to unlock all the achievements.

EDIT March 31, 2023: I ended up figuring out the problem months later. It was an issue with my external CD drive. It should work on Windows 11.

Also, if it asks for a product code, what I did was I used the product code it came with even though the game was used, and it worked. If you read the threads on here, GFWL must have done something on the back end where it accepts used codes now. Some have even said they used codes from different GFWL games and even just typing random letters and it worked. I can't guarantee this will work, but for many it seemed to. If you don't want to go that route, you can always buy the disc new. Should have an unused code obviously, and they are not super expensive either compared to other old games. 30 USD on Amazon right now.

All of this is to say, GFWL is very old and prepare for a headache when trying to work with it. I hope this helps you and anyone else who stumbles on it.