I just opened this app to test it out. In order for this app to work, when you create a new user, you need to be sure and select a user role of Employee as Stephan mentioned. You also need to make the password for this new user welcome as this is the default password used by the app. If you do these two things, you'll be able to login with your new employee username and create an expense report.
Hope that helps,
Thanks for you response.
When I downloaded the app it only includes Project, System, Layouts, Expenses & AppcloudServices modules. And I logged in as admin but I was unable to create the user! I think is because the User Management module is was missing.
I imported User Management module and created a user with Employee role and password as welcome. With the employee username and password I was able to login successfully but I tried to create new expense report it again gave me the same error "You need to be an employee to do this."
What am I doing wrong here?