If you declined to receive notifications in the first place, try to reinstall the game and agree to get notifications in the tutorial. Do not worry, you will not lose your progress if you follow these steps: 

1. Write down your Player ID (e.g. John#12345) somewhere so that our support team can manually restore your account if something goes wrong.

2. Make sure you are signed in to your Google account and that Cloud synchronization is enabled in Options before deleting the game. 
3. Delete and reinstall C.A.T.S. from Google Play Store. 
4. Launch the game and agree to get notifications in the tutorial. 
5. Navigate to Options and enable Cloud synchronization. 
6. You will see a pop-up asking if you want to restore your progress. Tap "Yes."