I have done that (several times) - it will only permit me to use an existing Cloudflare domain - obviously I am trying to make this domain an ‘existing’ domain!
Glad you got this sorted @gt8vps. This thread has good background on the difference between a banned zone and a temporarily banned zone.
If the error reads temporarily banned, wait a few hours and try again before contacting support. Temporary bans clear after a couple of hours. Full details in this thread,