Ensure the OBB file is not inside a subfolder. It must be directly inside Android/OBB/com.gameloft.android.zombieinfection/ .
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Download a robust file explorer like ZArchiver or MiXplorer from the Google Play Store to handle compressed archives. Ensure the OBB file is not inside a subfolder
The application installer (usually tailored for older Android versions). zombie infection gameloft apk obb fix