Redemption for the "beta key" ended 2013-12-31; see http://eu.finalfantasyxiv.com/lodest...cfd34f04d6f9db
So I'm afraid the two rewards (mog cap and cait sith doll minion) are now unobtainable.

However, entering your CD key in order to be able to activate the game should still work just fine - just install the game, run it, let it patch, and it should give you the option to enter it from there.
Otherwise, go to Mog Station (http://sqex.to/Msp) and take it from there.