The OBB does not appear to be downloading. The “Failed to Verify” is not always happening. For some the OBB Downloader pops up and the validation progress bar goes to 100% always crashes. For others it just goes to a black screen and crashes immediately.
One scenario for a user. Downloaded the game and just got the black screen immediately and crashes. Then deleted and re-downloaded multiple times with the same scenario. Then on 4th install attempt got the progress bar with the XAPK File Validation failed.
When the OBB downloads from the Google Play store itself it seems to always works fine.