Accessing a Shared Mailbox with Outlook for Mac

Open Outlook > Tools.
Under Tools choose Accounts.
The Accounts dialog box will open.
Click on Advance > Delegates.
From the Delegates, screen select the plus sign under the “Open these additional mailboxes.”
Type the name of the mailbox you like to add, select the mailbox from the list and choose Add. Click OK.
Close the Accounts box.
The mailbox will display on the left side of Outlook.