Your browser doesn't support Javascript, which is necessary to start own downloading. Javascript is also essential for viewing ad elements on this site, hence mentioned limitation was established.
Solution:
Permit Javascript-ing in your browser settings, eventually put Game Downloads website into a zone, that allows this scripting. Javascript should be implicitly allowed by the browser, so if you're in trouble, ask your system administrator, why is scripting forbidden, and request him/her for allowing it.
Then continue at Game Downloads server's homepage.