Something might be broken then, because when I go to the developer dashboard I see “User is not Authorized” and “Application under review”.
EDIT: To clarify, there is already an app developed under this account (8574680) and I had access to the beta of the new DM API, but, if I understand correctly, my “legacy” app doesn’t have access to the webhooks API unless I have access to the new developer dashboard, which I don’t.