After installation you can directly access the plant content through the built-in plants browser. Loading a plant into the scene through the browser will create a procedural geometry object which gives you advanced options about different viewport modes, Level of Detail options, several variations and ages as well as different seasons.

Just start the installer that comes with the App Store download. The 3ds Max 2014-2020 and Maya 2015-2019 plugins are installed in the appropriate folder, plugins for older editions of 3ds Max will be installed in their program folder. The content files will by default be in installed to the Program Files/Laubwerk directory. This path is customizable. The uninstaller is accessible from the Start menu. Since some parts of the Plants Kit are installed into the programs folder, the installer will need admin privileges.