For massive text files that need to be opened on a Mac after installation, or TextMate are recommended for managing large data.
Double-click the downloaded .dmg file to "mount" it. It will act like a virtual drive on your desktop or in your Finder sidebar.
If you are looking to download older operating systems as .dmg files, you can use official links to create bootable USB drives: OS X El Capitan 10.11 OS X Yosemite 10.10
are also available through archive.org. Troubleshooting
Click the download link from your browser. Safari typically saves these to the Downloads folder, which you can access via the Dock or Finder.
Downloading and installing a Mac DMG file involves acquiring a disk image ( .dmg ), mounting it, and copying the application to your computer. How to Download and Install a DMG File
Once the copy is finished, right-click (or control-click) the mounted drive on your desktop and choose "Eject". Downloading Older macOS DMGs