Installation Website
QGIS is a free and open source Geographical Information System.
Follow the instructions provided by the installer you downloaded.
Before installing QGIS, you must first install Python 3.6. Use the 64-bit installer if you’re using MacOS 10.9 or later, or the 64-bit/32-bit installer if you’re using an earlier version of MacOS.
When you click on the installer, you will see this page (the image shows version 3.4, but the image will be nearly identical for version 3.6):
Double-click on Install QGIS 3 LTR.pkg
to install the software.
You may need to change security & privacy settings to allow app downloads from outside sources.
Launch QGIS 3.6 Desktop 3.6.0. A new project will look like this:
Instructions are modified from Michelle A. McSweeney