Cannot add custom domain

I want to use but it says it’s already used.
However, is a public domain that anyone can register for a subdomain, like
Is it possible to change this please? I could make a web redirect too but i would rather use it as the main domain name

Howdy @masckmaster2007 and sorry for the trouble! I think I just got that cleared up for you - could you try again and let me know if things work better now?