1. Go into Calendar > right-click on Shared Calendars > Add Calendar > Open Shared Calendar...


2. Click Name.. and search for the user whose calendar you want to add


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- Change Calendar Permissions - https://smolin.freshservice.com/support/solutions/articles/4000058606

- Fix for error when adding shared calendar - https://smolin.freshservice.com/support/solutions/articles/4000058604