The app uses the sample app provided by DJI in Android github repo.
Simply click on your google map and copy the full coordinates in form of
-33.705268,151.098124
then paste into this app as demonstrated in the screenshots.
You also need the flight height and descend height and option to whether land at delivery point or return home.
See the screenshots to understand the height inputs.
It waits at 1.5m above surface (when you enter right heights) for about 10 seconds and then comes back home at the height set at your DJI Go app.
Make sure you understand and abide by your country laws before using this.
Make sure you copy the right coordinates and you know where it is to avoid landing in dangerous areas.