Creation of device ID and token for DPS API "access denied"

We are in process to get the access_token but there is problem:

Through this server: https://aex.stage02.publish.adobe.com/ we are able to create the Device ID and Token but access_token is not created using PHP example or curl command. We are getting the error of "access denied".

Through this server: https://aex.publish.adobe.com/ we are encountering the below problem:

@ERROR Error when getting the device token. Reason: User is not authorized to generate IMS Refresh Token.