LDAP in Grafana Portal - Need help to complete the

I have grafana free version installed in one of our server. I am trying to implement LDAP in my grafana portal. Used the following link to setup LDAP:

I can see the LDAP option in admin portal without any error. But while searching for user, I am getting the error:
No user was found in the LDAP server(s) with that username

I tried the steps multiple times. But couldn’t identify the exact reason. Can someone please help me on this?
Do we have any other urls which can be referenced?