ScreenConnect is the software that we use for remote assistance of our clients.
When click the "JOIN" button to join a session, you will be presented with the following (or a variation on it due to using a browser other than Mozilla Firefox):
Please select "Open with" rather than "Save" and select an appropriate application for Java Web Start (IcedTea being an open-source such application).
A progress bar will then appear indicating that the application is downloading. When complete, you will be presented with the following:
Elsinore Technologies are the authors of Screen Connect and it is therefore OK to trust content from them. Please allow the application to run.