How to view or add a shared mailbox as a folder under your account via Outlook webmail?

Step 1: Sign into the user account via https://outlook.office365.com/

Step 2: Right-click on Folders on the left pane and select Add shared folder.

Step 3: Enter the shared mailbox in the Add shared folder prompt.

Step 4: Click Add.

Step 5: The shared folder will appear on the left pane.