Hi @jayrc
Please use Basic and a base 64 encoding of client id, column and client secret instead of access token. The algorithm looks like the following
Authorization: Basic " + base64_encode(client_id + “:” + client_secret)
If you are testing this through Postman, please add the client ID and client secret under Authorization >> Type >> Basic Auth. For username, please add the value for client ID and, for password, the value for client secret.