This usually isn’t a Make issue. That error comes directly from the whatsapp api
It means the phone number you’re using isn’t fully registered or approved on the WhatsApp provider side. I’ve seen this happen when the number hasn’t completed verification or the business account setup isn’t finished.
I’d double check that the number is active and able to send messages in the provider dashboard, then reconnect the WhatsApp connection in Make. After that, the scenario usually runs fine.
You can use WhatsApp Business Cloud’s Register a Sender module to register your WhatsApp account.
If you’re encountering the “Account is not registered” error, this step is mandatory. The full process is clearly explained in the official documentation—please refer to it for detailed guidance.
I’m also attaching a screenshot from the documentation for reference, which highlights the relevant section. Registering the sender using this module should resolve the issue.