The download button opens the iTunes App Store, where you
may continue the download process. You must have iTunes installed with an
active iTunes account in order to download and install the software. This
download may not be available in some countries.
From ByteCheetah LLP.:
The app is a quiz asking 20 random questions per run about any field in the world. The user has the choice to skip questions. The correct answers is to be chosen in multiple-choice mode.