Nifi - Initial admin unable to add users

This is because the initial version of the secure version of NiFi is running in single user authentication mode. To add users, one would need to change this, and be able to edit the users and policies that can login and interact with NiFi, you will need to integrate NiFi with another login provider, such as LDAP or Kerberos. Once integrated to allow logins from LDAP or Kerberos, NiFi can be logged into from the initial admin account and be configured as desired.