You can think of the OnTrack App as OnTrack portion of your site in an app-wrapper. It behaves essentially the same as when you access OnTrack functionality from a web browser. Though it does have functionality limited to end-user functions (no admin options are currently available). The following are the exceptions:
Before a user can first access the app, they must already have a fully functional LMS account. See this article for further information.
In addition to supporting Standard Notifications, which is to say via email and the "In-App Inbox" (which despite the name is through the LMS, not via the mobile app), OnTrack also supports real-time push notifications via the OnTrack Mobile App.
See this section of the Notifications Compendium for information about what notifications are available for OnTrack.