This usually means the OBB folder is in the wrong place or is named incorrectly. Double-check the folder name.
Use an app like ZArchiver to handle the OBB placement. Installation Guide: Step-by-Step Step 1: Download the Files modern combat 4 apk obb offline fixed
Ensure you are using the "Fixed/Patched" APK and that you launched the game with the internet turned off for the first time. This usually means the OBB folder is in