This app was never released to the public, only available as a Japanese version. It was found on japanese eShop servers, and is most likely intended to be a demo, for stores to show off amiibo functionality. Upon launching, you are greeted with a configuration screen. To go to the actually app, you need to press (B). The top screen shows a [?] block, and the bottom screen shows an amiibo logo, where the scanner is. Tapping an amiibo will result in Mario's hand hitting the [?] block, resulting in one of 6 coins - Mario, Luigi, Toad, Yoshi, Peach, or Bowser. This coin does not provide and items or advantages in other games on the console, and scanning an amiibo twice will show an X on the top screen. The odds of getting each coin are configured in the configuration screen mentioned earlier.
In this app, When you tap an amiibo you earn a mario, luigi, yoshi, toad, peach or bowser coin to
A video showcasing this app can be found here.