I bought the game on PC for my wife using her SquareEnix account and I bought the game for myself on my PS4 using my SquareEnix account and my playstation account. Can I use my account and character on the PC? I'm getting an error message, so I'm assuming the game is tied to the account and I can't switch from one platform to the other?

I know the game servers are down tonight for a while for a patch. I'm not sure about playing your account on PC if you never bought a PC client. I do know that you can add a platform to your account if needed though, which also should come with the 30 days. Since you can usually get the PC version on sale for $15 on Amazon, you could do that instead of paying that month. Again not sure if you have to or not, check again when the servers are up.

You can play your account on every platform for which you've purchased the game (and registered the product key to your account). If you purchase copies for both the PC and PS4, you can use your same account and characters on either platform, and you can switch back and forth any time you want (though you can't be logged in from more than one at any given time).

So, the roundabout answer would be that if you want to play on the PC, you'll need to buy a PC copy for yourself and register it on your account. Likewise, if your wife wants to play on the PS4, you'll need to buy a copy for her and register it on her account. When you log into the Mog Station (account management site), it will show you which versions of the game you've registered on your account.

Go to Mogstation if you don't see that you have the PC licence registered to your service account then no you'll have to purchase a PC license and attach it to your SE account. You can't just willy nilly log into the client with your account on a different platform.

I should add that you SHOULD be able to add a PC licence to your account directly from mogstation but you will most likely have to pay for it.