To receive push notifications, it is first of all important that you allow them on your phone. Depending on your phone, you can find this setting via:

iOS: Settings > Pay2Wash > Notifications
Android: Control notifications on Android - Android Help (google.com)

In addition, it is important that you enbale push notifications in your Pay2Wash account. To do this, go to 'My account' > 'Notification settings' and select the option 'Notify me via push notifications'.