Update Stopped, then New Download Stopped

I started a Mac Zoom update which stopped and did not complete. I could not even close the update window.

I used an App Cleaner & Uninstaller to completely uninstall Zoom.

Upon downloading newly and reinstallation, the installer completely stopped again with the message window “Waiting for other installations to complete.” When I try to quit the installer I get this message, “The Installer is busy. The window can’t be closed.”

So the install won't complete, and the install window cannot be removed from my desktop.

Any idea how I can correct this situation so that I can download Zoom again?