Click on Account Settings and then Account Settings again
Under the E-mail tab, click on "New..."
(optional) Fill out "Your Name" field
Enter the shared inbox into "E-mail Address" field
Click "Next"
Click "Finish" and then restart Outlook
Note: It may take a few minutes to load all of the shared mailbox contents. Once loaded, all contents can be accessed by selecting the shared mailbox displayed on the left panel in the Outlook window.
Mac:
In Outlook, click Tools
Then click on Accounts
Select your account from the list
Click on Advanced
Click on Delegates
Click the "+" under "Open these additional mailboxes:"
Search for the name of the shared mailbox, select it, and click OK.
Note: It may take a few minutes to load all of the shared mailbox contents. Once loaded, all contents can be accessed by selecting the shared mailbox displayed on the left panel in the Outlook window.
In the upper right corner of the screen, you should see a profile icon. Click it and select "Open another mailbox." In the search bar, type the specific email account and select Open.
Your browser will open a new tab displaying the email account contents of this shared mailbox.
Calendar
Within the Outlook application (Win / Mac), select Calendar from the panel on the left and select the specific mailbox calendar you would like to view. Calendar contents should display within a few minutes.
With Outlook online (Win / Mac), click the small squares icon on the top left corner of the window and select Calendar. Calendar contents should display immediately.