Can't create a new Character on Solis Challenger Heroic server

Hey!

I am a returning player (haven't played for years) and I am trying to create a new character on the Solis Challenger-Heroic server. I can't seem to do it, it's showing me "You cannot create a character in this world".

What could be the cause?

Apologies in advance if the question is stupid.

Cheers!