Official Apple Support
Note on 32-bit Apps: Unlike Mojave, Catalina 10.15.7 is the first macOS to drop 32-bit support entirely. Do not upgrade if you rely on legacy software.
cd command to navigate to the location of the DMG file./path/to/dmg with the actual path to the DMG file and /path/to/usb with the actual path to the USB drive:The Final Polish: As the 21st and last release of Catalina, version 10.15.7 was designed to resolve nagging bugs, specifically fixing issues with automatic Wi-Fi connections and iCloud Drive file syncing.