If you have made several attempts and the MFA and still not working:

For Android:
  1. Go to the Google Authenticator app on your phone
  2. Click on the 3 dots located at the top right of the screen
  3. Click on Configuration
  4. Click on Time Correction for codes
  5. Click on Sync Now
For Iphone:
  1. Go to the iPhone Settings
  2. Select General
  3. Select Date & Time
  4. Enable Set Automatically


After that please try again to add it on your Revmax login.