Pre-ordering PS4 Heavensward through retailer

Desperately looking for some explanation on how this is all supposed to work though it seems my situation is entirely unique as no one I've spoken to seems to have any clue as to what I should do.

I got Final Fantasy XIV for the 2.0 launch on the PC but started playing on the PS4 when I got one which I found to be much more fun. For that reason I'll be playing Heavensward on the PS4.

I put my 18 digit pre-order code that I got from EB Games Australia into the page on the FF14 website and clicked PS4 and it gave me a 12 digit code saying I need to put it in the PlayStation Store. So I did.

All it did was download some file which I can only imagine is the initial patch being dowloaded...onto my PS4 disk of the original game? I'm not sure how it works.

MY QUESTION IS THIS.
The PS store has nothing to do with my FF14 account, which I initially made for PC. How did putting the code into the PS store add HeavenSward to my FF14 account?
Do I need to put the 12 digit code elsewhere?
Do I need to buy the game for the PC as well even though I have no intention of playing it on PC again?

What am I doing wrong!?

Please help me, anyone. I am desperate to know what on earth I'm supposed to do. I have emailed support but no response. PLEASE.

I'm not with tech support, but I do play on PS3/4. If I remember from when I started playing 2 years ago at launch, you have done everything you need to do for now. The 18 digit code tell SE that you have purchased the game amd gives you access on the 19th. If you look under your mog station services info it should have heavensward preorder or some such thing listed. The 12 digit code tell the PSN tore that you bought the game and allows you to down the client update. Which you said already happened.

When you get your actual game (I'm assuming you got the physical copy since no one is saying anything about digital preorders) you will probably get 2 more codes: an 18 and a 12. You will need to register that18 with SE also because the is the actual game access code. The 12 is for the PSN again but I'm not sure if you need to actually use this code since you already have the updated client but you might as well because it really wouldn't be helpful to anyone with out the 18 digit license code.

Again not tech support. This is just what I remeber from 2.0 launch.

you must have already linked your SE account with your psn account when you started playing, so by using the code in PSN and downloading the client patch, then I would assume your SE/ARR account would have the expansion data on it too :)

Did you already recieve the pre-order bonuses? SE site says that they would be delivered when entering the code, but I've not gotten mine yet?