The game is not detecting it. Ensure:
Review troubleshooting tips for modern Android versions (11+) that restrict OBB folder access on Are you encountering a specific error message when you try to launch the game? Main.8.com.rockstargames.gtasa.obb File Download Fix
Troubleshooting GTA San Andreas : How to Fix the "Main.8.com.rockstargames.gtasa.obb" Download Error If you are trying to play Grand Theft Auto: San Andreas The game is not detecting it
Inside the obb folder, check if a folder named com.rockstargames.gtasa exists. Main.8.com.rockstargames.gtasa.obb File Download Fix