Please follow these steps to troubleshoot:
1. Make sure the incoming call notification is turned on in the App and Allow realme Link App to access phone notifications.
Path: realme Link > Find your watch card > Watch details > Turn on Notifications
2. Make sure the watch is connected to your mobile device.
3. Make sure the realme Link App is not closed in the background.
4. Make sure the Do Not Disturb mode is turned off on the watch.
Path: Swipe down on the home page > Make sure you have disabled DND icon (moon icon)