The state is NOT an oAuth token
State is used to pass information into the Auth flow that is then passed back to you when the user comes back from logging in to Twitch and providing access to your Application.
Since you don’t know what it is for, you probably don’t need to use it.
@Optimal you are looking at using https://github.com/justintv/Twitch-API/blob/master/v3_resources/subscriptions.md#get-channelschannelsubscriptions for what you are after.
(But if you have cdnthe3rd’s oAuth access to his subs list there is an alternative method but the above should suffice as you only need to oAuth the user)
I’ve done stuff for you guys before so if needs be you can drop me a line and I’ll see if I can squeeze you in if you get completely stuck