Here is the full trail of clicks for Outlook Web App Zoom Calendar sign in.

First, click Zoom in the event's ribbon, then Allow:

When the sign in window loads, scroll down and click SSO. (Don't put your info in the fields email address/password because that's just for regular users.)

In the domain box type commonwealthu-edu (not dots) or copy and paste from here - then click Continue

This should sign you right in since sign in is connected to Microsoft. If not, enter your email address and password on the single sign on page and click Sign On, then you should see a meeting link in your calendar item/invite.