We are closed for registration at the moment :(
Do get in touch with a tabletop.social user to get an invite.
Other server exists, namely: http://dice.camp , http://ludosphere.fr , http://rollenspiel.social
Here is a website with a list of instances https://instances.social/
Alternatively email host AT tabletop DOT social with a few words on how you are not a spam robot and maybe your favorite meeple colour OR d&d class.