"Invalid user credentials" in keycloak

I am trying out get the access token from the super user so that I can the same to create new users in key cloak, I have deployed keycloak in wildfly and when I try to do the get call, I am getting Invalid user credentials as response,
How to know the actual credentials?

And when I try to update the password from the console, I getting the error message like below.

Since I am new to this and din’t find enough information from internet also, any kind of help will be appreciated .