Not able to login user

I am trying to send message user to user( one to one ). Found one library: https://github.com/deleolajide/ofmeet-openfire-plugin but getting error of authentication (401).

I was trying to login postman: 127.0.0.1:9090/plugins/restapi/v1/chat/{username}/login

error in error log:
2018.12.03 15:30:31 DEBUG [Jetty-QTP-AdminConsole-3637]: org.jivesoftware.util.CertificateManager - CertificateManager: Subject Alternative Name Mapping returned [127.0.0.1]