Same here. Stuck on the gray background image with the buildings and a car after allowing the app to access location. I've given all the access privileges the app was expecting and even payed around a bit with the ones on the GSF, since the Aurora Store shows that as a prerequisite.
Sadly, after a comment on Google Play, the only answer I had from the owner was 'rtfm'. Funny enough, the only technical solution I've found on their website is 'reinstall the app', 'reboot the phone', and such kind of Micro$oft inspired solutions.
If anyone figures out how to run the software, or what's going on, please share. In France several cities made the choice of using only this app for public parking payment so I'm stuck with the need to find a working parking meter every time I have to take my car.