any idea how can i make the data app recognize who is the user who is using it?

Hello

I have KINME Flow, that used for get a reported Hours for Employees.

This WF is connected to a DATA App,

I want to let this app to be used as following

1- The Manager log on the app

2- the Flow check this username or any other way to get him only the data of his/her Employees

3- there is an icon/button that activate send the data via email to this manager.

any idea how can i make the data app recognize who is the manager using it?