When you press the Create Admin User button, you did not see anything, but in fact, the admin user has been created and the password has been set. If the admin user already exists, the password has been reset. It is not necessary to press the Update Admin User Password button.
After pressing Create Admin User, you must be able to log in (in the client) with the administrator user name (defined in the Modeler) and the administrator password (defined in the Mendix Service Console, Common Configuration, Admin User Password field).
What "create admin user button" are you referring to exactly? Do you mean the "New" button under Administration | Users?