Not sure if you guys are aware yet, but you must uninstall the beta version.
Then re-download the retail version. They are not patching the beta for the head start release (Although I'm sure I read that they were going too)
Here is the link to start the process all over again.http://www.riftgame.com/en/headstart/index.php
At this point in time you CAN'T download the game just the launcher, will be a few more hours till you can download the full program.