However, this architectural shift is what makes downloading Catalina today tricky. Apple implemented stricter Gatekeeper protocols and notarization requirements. For modern users accustomed to the relative openness of older macOS versions, Catalina felt restrictive. Yet, this hardening was the necessary groundwork for the security standards required for the upcoming Apple Silicon transition.

Before downloading, ensure your Mac is compatible. macOS Catalina supports: Early 2015 or newer MacBook Air: Mid 2012 or newer MacBook Pro: Mid 2012 or newer Mac mini: Late 2012 or newer iMac: Late 2012 or newer iMac Pro: 2017 or newer Mac Pro: Late 2013 or newer

After downloading, the installer will launch automatically. You can quit it and copy the Install macOS Catalina.app to a USB drive or another Mac.

The defining characteristic of macOS Catalina was the removal of support for 32-bit applications. While Apple had warned developers for years, the release of Catalina forced a "Great Schism" in the Mac software library.