PC account established, but PS4 version (recently installed) is using old account inf

Greetings friends, I hope that this finds you well.
I have a PC account that I have been enjoying and playing with friends. I recently heard that I can buy the client again on the PS4 and play it there, too. I want to play the same characters that I am playing on the PC- but after I purchased the complete edition on the PS4 it had the Username field on the client already filled in- an old username from a free trial of the game that I had tried a long time ago. It would not allow me to change the username. I went ahead and entered the password for the username that it already had entered into the field and started the client download process... but I am wondering- how do I link it so that the PS4 client logs into my PC characters if the two usernames are now different? I tried to find a serial key or code somewhere on the PS4 version so that I could enter it into the MOG station and link the accounts, but it said that that was not the way to do it and that I would be given the option to link the accounts during the PS4 installation process... but I don't see that anywhere.

Thank you.

You link your Sony account to a single XIV account (This automatically registers your purchase so you don't receive a key). Sounds to me like you linked your Sony ID to your trial account which you abandoned, and started a new one on PC. You're going to need to talk to support about the issue as there's nothing player side you can do.

This makes sense in retrospect... sigh. Thank you very, very much for the reply. That is EXACTLY what happened!