Auth Token for Non Web Application

I am working on some custom on-stream notifications for a client, and I need access to her subscriber list. I have created a GameWisp account and a new application in the integration panel, but am not sure how to get the authorization tokens I need, since the documentation seems exclusively targeted towards web apps. What, for example, am I meant to use as the Endpoint/Redirect URI?

I should be able to interact with the API through simple HTTP Get requests, so it shouldn't matter what sort of agent is sending the requests, right? I tried the following in Chrome:

https://api.gamewisp.com/pub/v1/oauth/authorize?client_id=0169de9eb875a5ca42ac760ad765faf420a6c31&redirect_uri=localhost%2Foauth2callback&response_type=id_token&scope=read_only,subscriber_read_limited&state=0

But the response is {"error":"invalid_client","error_description":"Client authentication failed."}

What am I doing wrong?