How can i get the username and password of logged in user in kibana plugin 6.8?

how can i get the username and password of already authenticated logged in user in kibana plugin 6.8?

I have created a plugin in 6.8.0 kibana

I want to pass the username and password to the another app inside the iframe

This is not possible to do with Kibana, with any authentication provider. If you want users to have the same user/pass in kibana and another app, you can setup SAML, OIDC or Kerberos auth if that other app supports it and the same account will work on both.