I have downloaded the full version on Mac. I am using Indesign CS6, but it is not shown in InDesign.
I have tried to download the application and come to the official installation instructions instead. There is a page created by the developer that explains how to install it on your Mac.
Install instructions: http://www.croptima.com/help/inplate/v2/install.html
Note: Adobe Air is necessary to be downloaded (Windows/Mac compatible) in order to have the software registered properly.