To sync appointments with the selected Google Calendar, you need writer access. Please check with the Google Calendar owner in case syncing is required.
For Group Calendar:
For Unassigned Calendar:
Step 1:
To access the Google calendar, the owner must be logged into Google and go to calendar.google.com.
Step 2:
Click the three-dot icon and choose "Settings And Sharing" on the desired schedule.
Step 3:
Scroll down to "Share with specific people" > Click "Add People" and add the email address of the Google Account synced in Topline OS > set Permissions to "Make changes to events" > click "Send to Save".
The Google calendar should now be in sync with Topline OS.