I am sorry to hear you are experiencing an issue while adding your domain names to your Cloudflare account.
May I ask what is your domain name?
May I ask if you did set the domain nameservers to point to a given set of Cloudflare nameservers (from your CF account → as for example if you know them while having other domains under the same Cloudflare account, so you made “one step ahead”) before you have added your domain name to your Cloudflare account (which is resulting the error you are experiencing “is not registered domain”)?
Unfortunately, if that so, your domain DNS records should resolve correctly before switching to Cloudflare nameservers (or any other).
Regarding Cloudflare 1049 error, may I suggest you to try looking into below articles to troubleshoot the issue: