Hi @iurol
Have you done the configuration on ACC side
Ensure the package for push Notification is deployed
Create the service and mobile application
See documentation: https://experienceleague.adobe.com/docs/campaign-classic/using/sending-messages/sending-push-notific...
Also, a note: in the registration URL in the extension, please use the load balancer URL of your marketing instance, do not use the instance URL as you will not benefit from a load balancer.. if you don;t know your load balancer, you can ask Adobe Support to provide it for you..
Thanks
Denis