: You can find the macOS Catalina download page which will automatically open the App Store and allow you to download the installer to your Applications folder.
The quickest way to check for supplemental updates or security patches for 10.15.7 is through your system settings: macos catalina 10157 installer upd
The update specifically targets three significant issues that plagued earlier versions: : You can find the macOS Catalina download
Ensure you aren't trying to download Catalina on a Mac that shipped with Big Sur or later, as Apple often prevents "downgrading" via the standard updater. macos catalina 10157 installer upd