No problem with your internet connection?
You followed the article below, right?
http://www.tp-link.com/en/faq-818.html

Certainly, both methods.
There is no problem with the internet connection.
It's like the service does not create new accounts or it does not reply at all.

The camera is brand new?
Are you trying to re-register the camera to another new TP-LINK Cloud account or just register it to a Cloud account?
http://www.tp-link.com/en/faq-799.html

It is brand new and has a firmware newer than what is available for download (2.0.12)
(Im thinking of downgrading atm)
Logically it has not been registred before, but I did reset it pushing the button for 5s anyway.
It is my first camera so I do not have an account to add it to. I have to create a new one but still

TIPS: account sign-up failed.
Thanks for helping. By the way what is Fallback IP? I left it as it was then I put the IP of the camera.

SUCCESS: just now I saw a newer firmware 2.0.15. I downloaded it and
"Account sign-up successful"
So I blame 2.0.12 firmware

@evanzel

is the camera is brand new? if you have any problem you can read the article link below.

https://thebowgear.com/