“A DNS zone for this domain already exists under a different account” error creating DNS zone for “hxdesign.de”
(Deleted old account)
Hi, @hanswerner505, and welcome to the Netlify community site. 
I’ve confirmed there was a Netlify DNS configuration for this domain on a since deleted account (as you stated above). The configuration was not active and the account was deleted so I also removed the DNS configuration.
Please try adding this domain to the new team/site now. If this doesn’t work, please let us know.