Downloading "Repack" APKs and OBB files from unverified sources carries significant risks:
This is where most users fail.
The final path should look like:
/storage/emulated/0/Android/obb/com.rockstar.maxpayne3/main.123.com.rockstar.maxpayne3.obb
If the OBB file name is different, rename it exactly as above.
You will need stable Wi-Fi. Download both parts:
Use a download manager (like ADM – Advanced Download Manager) to prevent corruption during the large data download.