The download progress will appear in the Terminal. Once complete, the installer will be in your Applications 3. Alternative: Reinstall via Recovery Mode
You can download the official installer directly from the Apple Support website: download macos catalina 10.15.7 full installer
In the world of macOS, Apple doesn't keep old installers readily available on the App Store front page. Once a new major macOS version launches (like macOS Big Sur, Monterey, Ventura, Sonoma, or Sequoia), Apple hides the older ones. Furthermore, clicking "Get" on an old version often redirects you to System Settings > Software Update , which will only offer the latest macOS your hardware supports—not Catalina. The download progress will appear in the Terminal