The file main.8.com.rockstargames.gtasa.obb is a critical data component for the mobile version of Grand Theft Auto: San Andreas
Purchase GTA: San Andreas from:
Compatibility Issues: The "main.8" file must match the version of the APK you have installed. If they don't match, the game will stuck on a black screen or display a "Download failed because you may not have purchased this app" error. How to Install it Correctly
Since this is a portable version, there's no need for installation. Simply extract the downloaded file to a folder on your portable storage device.