Webex running on Ubuntu and other non-Windows platforms is literally a click away, in this case the CMR (Collaboration Meeting Room).
Webex is a fact of life for many people and for many Linux (BSD and other non-Windows) users, it has been a thorn in the side with people going so far as to set up virtual machines just to run Cisco’s collaboration software. While Webex is written in Java, it isn’t so simple to get running everywhere and apparently not all features are available for non-Windows users.
Most likely you are running up against the following message after logging into *.webex.com
Your browser,browser version, or operating system is currently unsupported
This requires the intervention of whoever is administrating the *.webex.com account and they can modify it in the following way.