This is the massive ~8GB to 12GB application usually grabbed from the Mac App Store. It contains the complete operating system infrastructure and is required to create a bootable USB drive or perform a clean install. Method 1: Download Catalina 10.15.7 via the Mac App Store
Open your web browser and click this direct Mac App Store link for macOS Catalina . download macos catalina 10157 dmg file install
If you are already running an older version of macOS Catalina and need to manually update it to 10.15.7 without using the App Store, you can leverage standalone update packages. This is the massive ~8GB to 12GB application
Your browser will prompt you to open the link in the or Software Update . Click Get or Download . download macos catalina 10157 dmg file install