Once you download the Revit plugin installer, you have to double click the .exe file. This will lead you to the plugin installation program and a new window will appear.
Click on Next and the installation program will automatically find the path where Revit is installed, detecting the installed versions as well.
Clicking on Next again will continue the process and let you choose which features of the Maxwell Render Revit plugin you want to install. Clicking on Install will complete the process and start the installation.