Same issue on PS4 :(

Gave that a shot as well, and unfortunately, I had no luck, but here's where I'm even more confused: my brother-in-law sat right next to me (on his PS4, not mine), registered with no issue, and began playing the game, so why is this error seemingly "selective" rather than a global, server-spanning issue? Why is it an issue at all!?

I'm now attempting the registration on a different (older model) PS4.

Same error/issue here on PS4, but here's where I'm even more confused: my brother-in-law sat right next to me, registered with no issue, and began playing the game, so why is this error seemingly "selective" rather than a global, server-spanning issue? Why is it an issue at all!?

I'm right there with you in your frustration and lack of response from devs.

I'm on PS4 and am having the same issue. I have tried five separate addresses, including one that was created five minutes prior to the attempted registration/linking, but I received the same error.

Here's where I'm even more confused though: my brother-in-law sat right next to me, registered with no issue, and began playing the game, so why is this error seemingly "selective" rather than a global, server-spanning issue? Why is it an issue at all!?

Same problem for me on PS4. 

It just says "this email is already used for account linking" I was super excited and even bought the upgrade pack. Now I'm just sitting at the home screen very very perturbed. I'm on Xbox btw

the same thing is happening to me