To open a shared Inbox, Contacts or Calendar folder:
In Outlook go to File > Open > Other User's Folder.
In the Open Other User's Folder window, in the User box, type the email address of the folder's owner, or select the user from the address book. In the Type box, select which folder you need to open (Inbox, Calendar or Contacts). Click on OK.
you will need to enter the in the “user” section