Click the download link from your browser. Safari typically saves these to the Downloads folder, which you can access via the Dock or Finder.
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 Download MAC dmg
To make sure I provide the right solution,g., a text editor, browser)? An to reinstall on a computer? A tool to read a long text file ? TextMate: Text editor for macOS Click the download link from your browser
A window will appear. Often, you simply drag the application icon into the Applications folder shortcut within that window. An to reinstall on a computer
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
If the app won't open, go to System Settings > Privacy & Security and click "Open Anyway".