Try this project. You need to supply the AppID for it to work.
This is a working example
https://x.thunkable.com/projectPage/6113727f3925f50012c178b4
Remember that Push Notification has different ID(s) for Android and iOS so use the one that fits your device,
Test can only be done with Android devices.
It does NOT work from the Web Live Test
You need to try it from the mobile and to see it working you might need to download and install the APK.
Happy Thunking!