Unfortunately, nsec.app doesn't receive push notifications reliably even after you've followed all instructions. This is on our radar, but we haven't figured things out yet.
Until then you'd have to keep nsec.app tab open on iOS to make things work, it won't work in the background like it should. 

 Thank you for the help!
However, I see a blank page on use.nsec.app, it seems it is not just a push notification issue.. is there any OS compatibility to keep in mind? I’m on iOS 16 

 Could you please try a different browser? Clear cache on this page? There are no compatibility issues that could cause blank page. 
If you clear cache make sure you remember the username/password or have key backup to login/import after clearing.  

 I tried it on safari and brave, cleaning cache and everything. Unfortunately, no result on my side 🥲 

 @brugeman small update.
Update phone to IOS 17.6 and now the page loads correctly. Thank you for your help, looking forward to starting using it! 

 Awesome, thanks for letting me know!