There are a couple of ways to access a shared or generic mailbox in Outlook for MacOS. Here are the ways to do so.
Open Outlook.
In the top left, click on the “Outlook” option, and then select “Preferences”.
Click on “Accounts” from the menu.
In the left hand column, click on the plus sign 
button at the bottom.
This will open a dialog box where you will sign in with the MVNU email address and the password, if you have this information.
If you do not have the MVNU email address or password for the account you are trying to access, you will access the account this way: |
Open Outlook.
In the top left, click on the “File” option.
Select “Open” from the menu, and then “Shared Mailbox…”
This will open a dialog box where you must search for the account by the email address until it shows up in the menu to select it from.
Click to highlight, and then click “Add”.
Close all menus and scroll in Outlook in the left-hand pane until you find the added generic account.
Please watch the video below for more reference.
Accessing a shared or generic mailbox in Outlook for mac.mov