Install Mobile Notifications package by Unity.
1. Go to Window -> Package Manager
2. In the Unity Registry section, find and install Mobile Notifications
3. Open Unity Mobile Notifications Settings from:
Edit -> Project Settings -> Mobile Notifications
Enable Reschedule on Device Restart to be able to send notifications even after device restart.
Select custom icons, small and large. If no custom icons are selected, app icon will be used.
Remember the identifier for each icon, you will need it when scheduling a notification from code.
4. Go to iDos Games SDK settings