Firefox users may get the  error "Unauthorized.  Sorry your session was expired.  Please refresh the page or log in again" when trying to get into a Zoom Meeting.  This because Firefox's Enhanced Tracking Protection is turned on. 

To turn it off click on the sheild icon in the address bar at the top of the screen and move the slider to the left to turn off Enhanced Tracking Protection. 

*If you do not see the sheild, click the back button to go back a page and you should see it.