Onyx International BOOX Nova2 User Manual page 121

8. If it shows "This device is not authenticated by the Google Play
protection mechanism" , it means that the authentication has not passed.
You can only wait for Google authentication to pass. After 5-20 minutes,
check again. If it still has not passed, you can continue to repeat steps 3
and 4 to re-authenticate, and then tap the Play Store to log in;