How do I open/add an office (shared) email account in Outlook for Office 365?
The following steps will show you how to add a shared email/calendar account.
If you are opening an shared calendar, be sure you know the username for that calendar. If you are not sure of the username, please contact Information Technology Services. Access to the office calendar is required. Access can be requested by an account owner using the Access Changes form.
Please see the following Microsoft Support article for instructions on opening a shared mailbox in Outlook for macOS:
Open a shared Mail, Calendar or People folder in Outlook for Mac