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 GazillaByte LLC:
TapeTrack for iOS allows you to manage your computer backup tape library using your own TapeTrack Server, a TapeTrack Server provided by your offsite vendor or any other Open Data Protection API (ODPAPI) enabled software or device.