Event Subscription not working

[synergieinsights (synergie)]

Description
I have created a webhook to send notifications when somebody start meeting and leaves the meeting. It is under my gmail account

Error
Notification not working

Which App Type (OAuth / Chatbot / JWT / Webhook)?
OAuth

Which Endpoint/s?
https://www.synergieinsights.com/castrol/zoom/ZoomJoinMeetingEvent

Screenshots (If applicable)

If applicable, add screenshots to help explain your problem.

[will.zoom (Will)]

Hi @synergieinsights,

As a first step, can you confirm that you have provided a publicly accessible write-to URL for the event notification event URL? Additionally, please ensure that you’re prepared to send back a 200OK response. If you don’t our webhook will silently fail.

Thanks,
Will