You can either click "Download" XML source link, or Click "get file for offline use" button to download the jar file.
Double click the jar file will run the simulation as application.
Right Click in the simulation region, and select "open ejs model" , then it will run EJS and load xml source.

You will need to download EJS and install it. (Google search:"EJS download")
Unzip  the downloaded file to C:\ , then  double click "ejsconsole.jar" to run it.