1
Download and open NLGL
2
Click on GTA IV or GTA V
3
Select the game folder
Paste the game folder’s path in the Game folder field (How to open Steam game's folder?).
4
Click Install modules
5
Find GTA IV or GTA V in your Steam Library
Right click on it -> Properties -> at the bottom in the Launch Options field add -nobattleye
6
Congrats!
If you’ve followed all of the steps correctly, you should be able to play GTA IV or GTA V.
To play the game:
Click on the Steam logo in the top left corner and click on Go Offline, then just start the game normally via the Steam Library.