Download Catalina 10.15.7 Full Installer [upd] -

Why download the full installer? You should create a bootable USB drive. This allows you to:

10.15.7 is the final version of Catalina. It includes all security patches and bug fixes released before Apple moved on to Big Sur. If you are going to run Catalina, use an older version like 10.15.0 or 10.15.3. Stick with 10.15.7. download catalina 10.15.7 full installer

Execute the "Install macOS Catalina" app from the Applications folder to upgrade the current Mac. This requires the target Mac to have OS X 10.9 (Mavericks) or later. Why download the full installer

Ensure you have at least 15GB of free space before attempting the download. download catalina 10.15.7 full installer

softwareupdate --fetch-full-installer --full-installer-version 10.15.7