Kurviger 1 works properly and is available for old owners on their Google Play.
As it works fine for all users, it maybe a problem on your device
or you have some blocker app limiting Android / Google services.
You can try a different device.
Kurviger 2 is a separate app with new features.
(and where development continues)
To re-install Kurviger 1, see the instructions in the documentation: