Cloudflare DNS with dynv6 domain

I don’t know how to set up my dynv6 domain with Cloudflare and I found no guide for this. When want to add the domain, I get the error “ is not a registered domain”.

Do you have any tipps for me?

You can not use official dynv6 domains in cloudflare. You can do it the other way round:
If you are using a domain in cloudflare you can delegate a subdomain to the dynv6 nameservers and use this subdomain in dynv6.