Thank you for contacting Telerik support.
The badge on the app's icon will be automatically set to the value contained in the badge
key of the notification payload for iOS. This happens only if the app is in the background when the notification is received. Unfortunately, the notifications sent from the portal does not contain this key in the payload. You will need to send a notification
with the following payload (using a tool like Fiddler or Postman):
"Push message for iOS"
More on the supported structure for the notification payload can be read here
In Android you can set the msgcnt
key in order to add a count for the notification entry in the notification tray.
Please, let us know if you have questions.