You would have to use javascript to capture the token from the URL, and then pass that token to your server.
Generally speaking implicit auth is for use when you don’t have a server, and with a server you would generally use “regular” oAuth, https://dev.twitch.tv/docs/authentication/getting-tokens-oauth#oauth-authorization-code-flow which gives you a token thats (usually) valid for four hours, but it’s gives you a refresh token that you can use to generate a new token.
Which is the method you probably started with but you were trying to store the refresh token in session which doesn’t make sense, since sessions are not reliable to store long running/reusable data such as a refresh token