Just make a new account.
Guessing people who spent money on cosmetics, or earned them through pre-orders or special events, ect would like to be able to use those items on another system.
I don't think this is new. I think you get same error if trying to log into Xbox One system with an account that was used on Playstation. It was just something no one noticed cause who would do that? Both systems are likely in same room, so no reason to no just use the same one all the time. And PC is cross with PS, so no issues if they log in there.
Now though you have people who want to play this portable, and are now noticing that Sony is trying to monopolize the ingame spending.
Or take Smash for example. If that came to PC and they allowed crossplay, would you not be annoyed if you had to re-unlock every character again. You have been playing this game for 100's of hours and you need to go and unlock everything again. And that is free unlocks. Toss in the money situation and I would be upset. Like having to purchase the DLC characters again for Smash Wii U on the PC. I would want it to be like Xbox/PC where you can play on both and both use same save data. Or an app on phone, wher I can log into my phone, tablet or even pc and continue the same game. Not have to rebuy all my yugioh cards or some shit. Yes, free game, but I want my account.