In order to have it on both, you have to buy them for both. The accounts aren't linked, so to complete any version of the game for the PC, PS4, etc. you will have to buy the packs again to complete each version.
I have pretty much all the game on my PS4, but only have the base game on my PC, because I would have to buy the same amount of stuff again to complete the PC version.
Also, one thing is that you can link your PC and PS4 idea if you make families and post them on the gallery, and you are able to transfer the families into the other version. It just depends on what you have that effects the stuff your family has.