If you have run the native programme (for me it keeps breaking up in the browser), run it from a dedicated unpriviledged user, without installing it on the system. (Run ./opt/zoom/ZoomLauncher.) If you have to log in (I couldn't change the input device without logging in), when your browser tries to open the not installed programme, copy the link and give it as a command-line argument to ZoomLauncher.
Looking forward to a working alternative.