Once you have → downloaded RealFlow 2016, extract the archive and open the disk image:
Drag the "RealFlow 2016" icon onto the "Applications" link to install the program.
Go to the "Applications" of your computer, search for "RealFlow 2016" and attach the application to your dock or open it directly.
When you start the application you will be asked to → license your copy of RealFlow 2016.