How to get ClientId/Secret Key (all credentials required to use OpenEMR Credentials)

I am very new to OpenEMR, I want to use its APIs but I am unable to use. Don’t know what I am odoing wrong. I have set up OpenEMR on windows using Xampp and then I also enable API from Admin -> Config -> Connector folder. Now I got to know that for API credentials I have to work as Admin->System->API Client. When i clicked on it and try to make client it says

Now please tell me the base url for local OpenEMR will be this ? “http://localhost/openemr/apis/default/” ?

I got error on this

{
    "error": "server_error",
    "error_description": "The authorization server encountered an unexpected condition which prevented it from fulfilling the request: Security error - problem with authorization server keys.",
    "message": "The authorization server encountered an unexpected condition which prevented it from fulfilling the request: Security error - problem with authorization server keys."
}

Please HELP me to get rid of this issue !!!