Add a shared mailbox to Outlook

Step-by-step guide

Open Outlook. Click the File menu.
Click Account Settings → Account Settings...
Click the Data Files tab → Settings...
Click the Advanced tab and Add...
Enter your mailbox name or email address and click OK. Click OK and Close on any of the open Outlook windows.
If you have permission to the email box, it should now show on the left-hand side of Outlook under your personal email box.

You need to use Outlook on your cell phone to do this.