Setting up account for calendar sync permissions

I have a user getting the message "Contact your system administrator. The application should be integrated with Google" when they try to set up a Gmail account for calendar sync.

Other users have been able to set up an account to sync, so not sure why it is different for this user and I am unable to locate any related permissions that might need to get set. Where would I find the permissions I need to set for this user?

Thanks,

Ryan