Hi Mayhan,
There is a demo app for this module in the app store, maybe this will help in setting the module up.
https://appstore.home.mendix.com/link/app/3020/Mendix/Push-Notifications-Connector-Demo
There is also another demo app on the github
https://github.com/mendix/MxPushNotifications/tree/master/test
Also, here is a how to guide with instructions to set it up.
https://docs.mendix.com/howto/mobile/push-notifications
In the demo apps I would look at what app store modules that they are using, and import those same modules into your application.