Hi,
Well, i had this problem in the first DLC, so i guess i can help you.
You will have to enter the PS Store, games, expansions, and select the BF 4 Naval Strike icon. You will be directed to the BF4 premium screen. You just have to search the DLC in the similar contents in this screen, there will be the download pack for Naval Strike.
I'm at work so i'm just saying the main steps to download. If this don't help you at all let me know, when i get home i'll send you the exactly steps.
