When calling Get-MgUserCalendar I get an error "The specified object was not found in the store." unless I have given myself delegate permissions on that person's mailbox. I am a global admin in O365. The purpose of my script is to forcibly add an event to user calendars as a reminder to do something.
I expect that the reason I can't simply have access to calendar IDs is due to security risk. Is there a way around this or a better way to get their calendarId?