Before you can input any of the codes, you need to find all the corresponding collectables in the campaign, here is the code for the fourth
04 08 03 07 02 06 01 05 09
05 01 06 02 07 03 08 04 09
I used the below vids, watch out for chapter 7 (Hideout) and 11 (U-Boat) as hes missing one on each. To watch them on the PS4, come to this guide and watch on TT, for me if I try to watch them on their youtube page it says a plugin is needed :(
Tip from JoelSnake
"Just a tip if some collectable doesn't show up on the specified location:
This happened to me on the 14th level when collecting the first Enigma (Code 5-2). I tried to reload checkpoint, but it didn't show up. I played so I got a new checkpoint and tried to reload again, and it showed up! This was at the beginning of the level so it would've been easy to just reload the level. However if this happens to you near the level-ending this "trick" might help you and save you some time!"