If you have an Android phone, you can get push notifications when topics you follow are updated etc, just go to your notification settings in your profile to active such push notifications. As of now, Iphone users cannot get push notifications yet. Instead, you need to rely on the notifications given on 99nicu (on my screen shot below, the nb "6" in the right upper corner)
This technology is called Progressive Web Application (PWA). IMHO is works so well that I will mostly access 99nicu.org from my phone now!