If you look at Barry’s code, his example uses response_type=token, which is for the Implicit Auth Flow, as shown by the docs he has also linked in the example. https://dev.twitch.tv/docs/authentication/getting-tokens-oauth#oauth-implicit-code-flow
The implicit auth flow returns an Access Token in the URL hash, and is intended for use client-side.
You’re using response_type=code, which is for the Authorization Code flow, documented here: https://dev.twitch.tv/docs/authentication/getting-tokens-oauth#oauth-authorization-code-flow
The Auth Code flow doesn’t return any URL hash, it returns a code in the querystring params, which your backend server needs to then exchange for an Access Token and Refresh token. This auth flow is for making requests server-side, as your frontend wont have access to the client secret needed to exchange that code for tokens.