The Titanfall Beta gae has opened to all Xbox One owners, meaning that no code will be necessary to download and play the game.
To download the beta, sign in to your Xbox One and head to the "New Game Demos" section of the Game Store and it will appear there. Also, in some Xbox Live regions you'll see a "Join The Titanfall Beta" link on the home page of Xbox One, next to My Game and Apps.
A PC version of the game (Beta) will also follow soon, according to Microsoft.
Microsoft invites Xbox One owners to play the game in order to test the game's servers before it launches March 11th.