Downloading as a DMG file is a common requirement for users looking to create bootable USB drives or install the OS on older hardware. While Apple does not officially distribute the full installer as a standalone DMG file, there are several ways to obtain it. Official Download Methods
Remove the quarantine attribute: sudo xattr -cr /Applications/Install\ macOS\ Catalina.app
Below is a focused, structured report covering what build 10157 likely is, risks of downloading DMGs from Google Drive, how to verify authenticity if you proceed, safer alternatives, and recommended steps.
Your Mac must be one of these models. If not, do not attempt installation.
sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume Use code with caution. Copied to clipboard (Replace "MyVolume" with your USB drive's name) Alternative Unofficial Sources