It seems there is an error in the Standard Account Activity API documentation for all activities here: https://developer.twitter.com/en/docs/accounts-and-users/subscribe-account-activity/api-reference/aaa-standard-all
The end point to add a subscription is incorrect. Right now it is:
When it should be
The first one, testing with different path, gives always an error telling the page doesn’t exist. The second one works perfectly and I was able to get my user datas from Twitter Webhooks.
By the way, right now we don’t need to provide any webhook_id to this endpoint to create a subscription (maybe after beta ends?) so the parameters paragraph for this end point is also wrong.