You may find:
If you've obtained a DMG file from a third-party source, here's how to install it:
Apple does not officially distribute this software as a standalone DMG file.
While Apple does not provide a .dmg , some third-party software repositories host installers. when downloading from non-Apple sources to ensure file integrity: Softpedia FileHippo TechSpot How to Get Older Versions
Simple integration with enterprise deployment tools. Official Way to Download Apple Configurator