Auth0 POC ,External API calling not happening?

As i am new to auth0, i am trying to call an Authorized Api (external) to my web application using Auth0.

var client = new RestClient(“http://path_to_your_api/”);
var request = new RestRequest(Method.GET);
request.AddHeader(“authorization”, “Bearer ACCESSTOKEN_OF_AUTH0MANAGEMENTAPI”);
IRestResponse response = client.Execute(request);

but the responce i am getting is unauthorized. same i tried with postman and the responce is invalid token.
When i try any Auth0 management GET api using the same token it is returning result.