My PS3 code was paired with a beta code in one email which looks just like this:

Welcome to the FINAL FANTASY XIV: A Realm Reborn Beta Test!

Please find your Beta registration and PlayStation®3 Promotion codes below:
Beta Registration Code
XXXX XXXX XXXX XXXX XXXX
For instructions on how to register your code please click here.
PlayStation®3 Promotion Code
XXXX-XXXX-XXX
Instructions for using your Promotion Code:
Step 1: Connect the PlayStation®3 system to a broadband connection
Step 2: Sign in to your Sony Entertainment Network account on PlayStation®3
If you do not have an SEN account, please register for one (more information on www.playstation.com)
Step 3: Choose Account Management>Redeem Codes
Step 4: Select Redeem Promotion Code - this brings up a screen to enter the code you have received
Step 5: Enter code and follow the steps on screen to redeem content
*Terms and conditions apply. Please visit http://us.playstation.com/support/te...vice/index.htm to view full PlayStation®Network terms and conditions.

Details on how to install the Beta on your PlayStation®3 console can be found here.

After registering your code you can log in to the test forums here.

Thank you for helping to make FINAL FANTASY XIV: A Realm Reborn the best game it can be!
www.finalfantasyxiv.com
The PS3 promotion code is what allows you to do the DL on your PS3, after linking your PSN to your SE Account. The beta key is good for PC or PS3. If you were already in the beta you don't even need to register one.

I've been in Beta since day one as Legacy so never was prompted to enter the Beta code included in my PS3 Beta email.

By the way, I did not obtain a code via the method in this thread. Just wanted to explain ^^