.RUHR domain requires an admin contact in Germany. This means that you need to set up a contact record for these domains that has Germany as the country. You will be asked to set this up upon checkout. If you already have a contact record with Germany as the country, you can select it from a drop-down. Otherwise, it will ask you to create a new one with Germany set as the country.

You can also set or change this information in your Dynadot account under RUHR Domain Settings.