[keycloak-user] Admin user in Clustered Domain Mode

Hi, We connected a Domain Controller and 2 Slaves. How can I create an admin user? There is a "--domain" switch, but the users created with it don´t work. If I create a admin user on a slave it works and after that I can use him on the other slave, because he is in the db. How is the intended workflow here? Greetings Marc