An app must be downloaded and installed before you can enter web conference rooms.
This is only required once or when updating the plugin to a newer version.
Or go to the Apple Store and download and install the tcConference app. This is the preferred approach as the app will have been thoroughly scrutinized by Apple. However there will be a delay of a couple of weeks from the time updates are submitted to Apple before they are available from the Apple Store.
Click for System Requirements
Click for Tutorial
This app does have known issues and may disconnect more frequently than normal. No further updates are planned.