You and me both bother! I have scouring this for days yet no one seems to have a really straight forward answer. Maybe you can work better than me with the information I know.
I know I was told you can use http://localhost as your redirect url.
I was also told you can use this website for the implicit code flow method: https://twitchapps.com/tokengen/
I tried putting the local host as in my redirect for my app and I tried going to that link and clicking “connect to twitch” but then it brought me over to my IIS and it didn’t give me token! So I don’t know what to do.
I know Oauth is used elsewhere but I never had to do this to get the token. For discord, I just clicked on a link that copied my token for me and then I was on the next steps. Here I have no clue what to do.
I hope you have better luck than me!