@Pushyrummble,
Unfortunately like your error says, an EA account can only ever be linked to one of a specific type of account in its lifetime, so if you've previously had a PlayStation account linked, you won't be able to link a new one. If you look at our unlinking article:
When you link accounts, it creates a lifetime link to protect you from malicious activity and help prevent performance issues in your games.
You can unlink your platform accounts from your EA Account if you want to link them to a different EA Account, as long as that EA Account has never had the same account type linked to it before in its lifetime.
That means if you unlink an Xbox gamertag from your EA Account, you can’t link a different Xbox gamertag to it in the future.
But just as a heads up, even if you could, your progress wouldn't carry over regardless since save data is stored at the EA account level, so if you unlink a PlayStation and link it elsewhere, none of that progress transfers. If you want to use your PlayStation progress on PC, then I recommend playing on the EA account that it's already linked to.