On request, download section has been extended with 'Enemy Territory game files' and updates. You need to be registered on this homepage to get access to the files, it is for free.
After installation, update the game, and connect to a server. A well configured server will send you the files need. If you get disconnected while downloading, please reconnect again. During downloading, you might expirence to be disconnected a few times.
Our FAQ about Enemy Territory contains solutions on most problems. If you still got problems, please make a post in our forum, and we will help you.