For TDM Portal versions 4.0, 4.1 & 4.2, this is working as designed. You must login with an AD/LDAP user accordingly.
For TDM Portal versions 4.3, 4.4 you can optionally disable native users. Ensure that
tdmweb.security.disableNativeUsers is set to false within the application.properties file if you want to login as "Administrator"