Are you trying to add a shared mailbox to Outlook on Windows? You’ve come to the right place!
Instructions
In Outlook, click File then Add Account. Enter the email address then click Connect.
Select Exchange
Select More choices, Use a different account, then enter your personal email address and password, then click OK.
Restart Outlook
If the mailbox isn’t opening after restarting Outlook, you likely didn’t use your personal email address in step 3. Remove the mailbox and repeat steps 1-3.