You just need a server side script
That is behind SSL
That server side script needs to be able to recieve POST requests.
Like a “login form to a website” would.
Twitch will be POST-ing to you JSON formatted data in the POST.
You can probably find exmaples and/or libraries over on Community Resources | Twitch Developers
Or you can check my Github where there is filed a PHP and a NodeJS example for consuming Webhook Transport EventSub https://github.com/BarryCarlyon/twitch_misc/tree/main/eventsub/handlers
You’ll also need a public web page that streamers would go to, in order to authorise your ability to read hype train data. So you’ll need a user oAuth web page.
You can then store or discard that user oAuth token as EventSub Webhooks uses an App Access Token to create Subscriptions to data feeds.
You would usually retain that token for “catch up” if you need to restart your system or experience any down time.
The “Handling Webhhook Events” guide is relatively comprehensive Handling Events | Twitch Developers