I'm surprised its part of the Play Pre-Order program considering its came out on PS3 a while back alongside the PS4 port being cross-buy with the PS4 version (meaning, people who bought the game for PS3 like me are getting the PS4 version for 'free').
In your case, the PS3 version didn't activate due to the PS4 version not being out yet. When that comes out and its on the PSN systems, your pre-order will 'unlock' the PS4 version and in turn, the PS3 version will activate as well.
Never pre-ordered anything on PSN, so I don't know how it works. But, I hope this helps you somewhat and you enjoy Journey when it comes out
. It really is a beautiful game and it must look amazing on PS4 :').