Note: Raindrop is not a standalone application, but a plugin inside of your existing CAD application. Once it is installed, it will appear in the ribbon under Raindrop Irrigation Tools. Raindrop is compatible with AutoCAD 2015+, windows versions only. There is currently no mac or linux version available.
You can download a trial of AutoCAD here.
If you download the AutoCAD trial, please install it before installing Raindrop. Close AutoCAD while installing or updating Raindrop.