These exercises are more difficult than the introductory exercises because you have to identify both the chord root and the chord type. If you haven't already tried the introductory modal exercises, you might want to start with them.
If you open the tab labeled 'Ionian' above, you'll see a row of tabs with different note names on each one. You'll be placed on the Ab tab to start and asked to choose the root and the chord type for the 2nd degree of the Ab Ionain mode. Select Bb and Minor7 (the second diatonic chord in the Ab Ionian mode) from the respective dropdown lists and click the [Submit] button.
The screen will confirm that the root and chord type you chose are indeed the one's it expected and you'll notice that the degree changes from the number '2' to a random number between 1 and 7. Now select the root and chord type at that degree of the Ab Ionian mode. If you select a root or chord type other than the expected one, you're prompted to try again.
Good luck and have fun!