Getting Insufficient Privileges error as Super User when trying to Connect Google Calendar

Getting Insufficient Privileges error as Super User when trying to Connect Google Calendar

Why am I unable to connect my Google Calendar with my account? I went through the pop up asking for authentication, and after which got the error (see 1st screenshot). Note that I'm the sole and super user of the account (see 2nd screenshot). Am I missing anything on this side or on the Google side? Also, it's regular Google calendar, not Google Apps for business or the like.