The notifications on the SubSidekick app will only be sent to one Apple or Android device at a time. For example if you download the app onto your iPhone and your iPad, notifications will only come to whichever device you have used most recently. You will still be able to use the app in both places at any time and always access the Available Jobs list from both; however, your notifications are just limited to either one or the other at any given time.
This also means that if you usually receive notifications on your smartphone but then you pull up our app on your tablet, you will start receiving notifications there instead until you switch back and use your phone again.