7z files, you need 7zip, so make sure you have it or if you don't have it, download it from here [After that, download FOSE and inside it, you will see a folder, go into it and extract its content into where your game is installed (in this case Steam/steamapps/common/Fallout 3 goty)
What is this? Even though this is not updated as of yet after the Anniversary Update, it is still required. If you are using Mod Organizer however, install it through Mod Organizer. Change the file's extension from '.fomod' to '.zip', then extract its contents to Fallout 3 goty/Data. zip file and extract the file that comes with it.
After it is done, press any key to close the prompt. Launch 'Patcher.exe' and it will install. How do I install this? Download the file and extract the files to where your Fallout3.exe is.
Makes the game 4GB aware and fixes the mod limit bug. I heavily recommend doing the patches/updates IN ORDER so that nothing goes wrong.