O.K , this means you are not getting response in OnSuccess, so may be you are getting an exception in OnException.
Then what is the exception now (after applying X509Certificates validation for unity_editor). And if you are not getting any exception in OnException then try to debug the issue by applying App42Log.SetDebug(true); in your start function and share the logs here.
I reccomend that you first test your script in Unity_Editor, so that it can be easily show the logs that what's the actual problem.