Installation problem when uses federated, file-based registry

Dear,

I'm using federated, file-based registry in WAS to authenticate user for RTC.

I successfully authenticated admin user managed by WAS to configure JTS.

However when I set up 'User Registry' in JTS, there are options.

- Tomcat User Database

- LDAP

- Non-LDAP External Registry

Q1) Which option should I choose when I use federated, file-based registry in WAS?

Q2) When I choose Non-LDAP External Registory or Tomcat user Database for user registry, it says "You need to be authenticated as a user from LDAP to import your user and assign licenses. Ensure the application container settings are configured correctly for LDAP, restart the server, and log in with a user from the LDAP directory to continue"

What should I do?

Any idea?

Appreciate your help.