If you’re getting a 404 it’s likely because you’re not making a request to the v5 api, as that endpoint doesn’t exist in v3 (the default) which would explain the 404. You need to add either the api_version=5 querystring param to the URL, or the Accept: application/vnd.twitchtv.v5+json header, to the request.
Can you show us the code you’re trying to use because that endpoint appears to be working fine on my end.