Android Studio with Scala plugin is required if you wish to compile it yourself.
Direct link to APK file: https://github.com/btcontract/wallet/blob/master/app/app-release.apk

Genuine Simple Bitcoin Wallet is ONLY available on the following app stores:

 

Xiaomi: http://app.mi.com/detail/105943

DO NOT install Simple Bitcoin Wallet from other places!