Some users have updated their phones to Windows 10 Mobile. The maaloo Apps are built for Windows Phone 8.x but run on Windows 10 Mobile too with some minor limitations.
The official update of W10M is the 10.0.10586.164. The 10586 is important, the last number is not so important.
One known limitation with W10M is the access to the SD-card. The maps on the SD-card are not detected by the app.
Some users had problems to start the app, if the app is installed on the SD-card. You should install the app on the internal storage of the phone in this case.
You should not use the Insider updates of W10M, not fast and not slow ring (14295.x) . There are potentially more problems. One problem is that the login to geocaching.com is not possible.
August 2017: The app also runs on Windows Mobile 10 up to version 1607, Build 14393, which can not be guaranteed for newer versions.