Thanks for the follow up @ieo! - I installed 4.6.8 and it’s working again. I had some issues to re-install 4.6.8, so I had to revert back to the manual process (via the Terminal window) to install an older version of Zoom:
$ pkgutil --expand Zoominstaller.pkg Zoom
$ cd Zoom/Scripts
$ ./7r x zm.7z
then I simply copied the zoom.us application in the Applications folder.