This is usually indicative of something wrong with your browser, your computer or something else.
I can also indicate a browser plugin/extension is interferring with your session and breaking the CSRF token.
This won’t get you anywhere as it’s not a third party issue. We deal with helping people with third party issues such as using the API.
The only time we deal with this issue is when a tool you are building is GETting the oauth entry point instead of redirecting.
But you seem to be having a general issue with the website, based on the steps you have copy/pasted, not a issue utilsing the third party products
In short: we cannot help you, you need to contact support as it appears to be an issue with your environment or something awry with first party Twitch.
So for further help