After your admin has added you as a member of a shared mailbox, close and then restart Outlook. The shared mailbox should automatically appear in your Folder pane in Outlook.
If your admin only recently added you to a shared mailbox, it may take a few minutes before the shared mailbox appears. Wait a bit and then close and restart Outlook again.
If that didn't work, then manually add the shared mailbox to Outlook:
Open Outlook.
Select the File tab on the ribbon, then select Account Settings > Account Settings.
Select the Email tab.
Make sure the correct account is highlighted, then choose Change.
Choose More Settings > Advanced > Add.
Type the shared email address, such as info@contoso.com.
Choose OK > OK.
Choose Next > Finish > Close.