When Shared Mailboxes do not appear on their own, you can use these steps to add them manually. 


1.) Open your Outlook Desktop Application. You should see "File" in the top left, go ahead and click it. 

*Note* The steps will be different on the Outlook 2024. This article is valid for 2019 and 2021 Outlook Versions


2.) Under your name at the top select "+Add Account"


3.) It will prompt you with this Dialog Box, enter the shared mailbox you would like to add.






4.) After you hit connect it will prompt you to sign into adfs with the password of this shared mailbox. Do not enter a password. The screen should look like this-

*Note* It must be this ADFS screen. It will not be a microsoft login. If you are not prompted with this exact screen you have entered the email incorrectly.







5.) You should hit the back button on the adfs screen to return to the username portion of sign in ->




6.) You will then clear out the username of the shared mailbox and put your OWN username. 




7.) Hit next, then enter your password and approve the duo push. 


8.) If you have access to the mailbox, it will prompt you with this -> 




9.) Hit done and restart Outlook. It should populate the next time you open the application.