Working now
It now works on iOS7 after I reset the Advertising Identifier setting and ran it with wi-fi on. The Lite version may require some type of ad tracking or web beacon. That's not stated anywhere and the developer's site is German only.
Not enough ratings yet to assess SwitchTrainer.
SwitchTrainer appears to be a legitimate app. AppsHunter Legitimacy Score for SwitchTrainer is 80/100.
Based on 80 of 100 points across 7 verification signals from App Store and developer data.