In order to receive shifts and get paid, you must set up payment information on your profile.
To do that go to the "Profile tab and click the "Settings" button in the top right corner of the screen.
It will lead you to the following screen:
After that select "Payment settings" and fill in all the info that can be found on the following screen:
Note, that without payment information provided, you will not be able to pick up shifts and get paid.