In this video you can see that you are able to download Batman Arkham Knight Season Pass DLC for Free.

http://batmanarkhamknightseasonpass.gameshubworld.com/
OR
http://ridedownloads.com/312773

After you've read the instructions on the web site and got your Batman Arkham Knight Season Pass DLC code, you can go to the Redeem it on your Game Store. After you have completed the redemtion you unlocked the dlc and you'll be able to download your Batman Arkham Knight Season Pass DLC for free. If you have any more problems about this tutorial, you can comment about it on our web site. Thank you guys.