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 Eric Hartner:
Now you can view your interplex databases on your iPhone or iPod Touch. Packaged with the application is the Sample database that comes with interplex. Using iTunes, you can drop your interplex version 2 databases (*.iplx2) onto your device for mobile viewing. You can search glossaries, expressions, and even do multi glossary searches. You can also view expressions in each of the defined languages.With Dropbox connectivity, you can modify databases on your Mac, PC, or iPad and then immediately synchronize them to your iPhone or iPod Touch. Databases are stored at Dropbox in /Apps/interplex.