You must own the game. The file will be installed automatically in the game folder when you install GTA IV from:
The file is named LaunchGTAIV.exe .
Before downloading any executable files, make sure to take the following precautions: launchgtaiv.exe download
Rockstar Games updated GTA IV to the "Complete Edition" in 2020, which replaced the old launcher system. This removed launchgtaiv.exe for many players, breaking older mods or save-game managers. You must own the game
If you encounter issues during installation or when running launchgtaiv.exe, try: launchgtaiv.exe download