If your Mac cannot run the latest macOS, you may still be able to download a "last compatible version" through these official workarounds: Check Purchased History
Once you have a DMG file (from any source), you must verify its cryptographic signature before opening it. Here is how: apple configurator 2 verified download dmg
) through a managed portal, you can manually verify its authenticity: Open the .pkg file : Double-click the installer. Inspect the Certificate : Click the certificate icon in the top-right corner of the installer window. Confirm Authority If your Mac cannot run the latest macOS,
Install directly from the Mac App Store – that’s Apple’s verified, current, and secure method. and secure method.