In AU's serviceportal you can require access for a shared mailbox
Shared mailbox: Enter the email address to search for the shared mailbox
Acess type:
Access Reason: Provide a reason for the requested access
An email will automatically be send to Mailbox Owner, who can approve or reject. You will be notified when Mailbox Owner has reacted.
When access has been approved you need to assign the shared mailbox to outlook
For removing an access to a shared mailbox, you need to contact your local IT-Support