You’re creating an Apple ID. And that is failing. That this Apple ID is for a developer account seems not immediately relevant.
Either your domain DNS or mail server setup is messed up, or the Apple servers used for creating an Apple ID are wobbling.
If this is your own domain and not (yet) heavily used, check your DNS and MX record setup. The mail server must have an A or AAAA record, for instance.
If this is a business domain managed by an IT team and is in active use (e.g. that of an established business, or an account at gmail or iCloud or such), DNS is probably correct and a transient issue at Apple.
Once DNS is verified, try again later, or contact Apple Support.
If this is a DNS configuration you’ve just recently set up (and you’re not entirely familiar with and comfortable with A, AAAA, and MX records), then maybe a tool such as mxtoolbox can help verify the settings.