1. From OWA (https://outlook.office.com/owa/), please click on your name in the upper right part of the window.
2. From the menu that will display, please click on "Open another mailbox..."
3. In the Open another mailbox window that will appear, enter the email for the Shared Mailbox that you are trying to access.
4. Click "Open" and if you have the necessary rights, the mailbox will appear in a different tab on your browser.