Runtime Error 400:Host can not register

Description
API that used to work for a meeting is not working and it is giving this error

Error
400: Host can not register

Which App Type (OAuth / Chatbot / JWT / Webhook)?
I tried it with JWY authorization and also using a Webhook and integromat

Which Endpoint/s?
The url to which I am sending the request : https://api.zoom.us/v2/webinars/".$webinarid."/registrants

The data sent
$zoomPost = array(
“first_name” => $firstname,
“last_name” => $lastname."-".$ref,
“email” => $Email,
“industry” => $ref
);

Screenshots (If applicable)
Error in the integromat screen