Here’s how you can find the notification tab in the mIKs-it application.
You can navigate to the home screen as highlighted below:
While on the home screen you will see the list of notifications that needs attention in the application. 
Tap on the notification you want to view then a pop-up screen will show up. (In this scenario, the user is notified about an incoming invitation from Elise Peeters)
You can then perform the action i.e., accept or reject the invitation. Once the action is performed, the application will prompt with a successful event message and the notification is dismissed from the notification tab. 