Fg-optional-mp-zombie-04.bin

You do not need to download this file if you only intend to play the single-player campaign.

fg-optional-mp-zombie-04.bin is an used in FitGirl repacks, typically for Call of Duty games, that contains specific assets for multiplayer or zombie modes. fg-optional-mp-zombie-04.bin

If you try to launch zombies or multiplayer without this file, the game will likely close or throw an error indicating missing content. You do not need to download this file

I can give you more specific troubleshooting steps for that game. typically for Call of Duty games

It holds data required for "Zombie" or "MP" (Multiplayer) modes.