(~2.86 GB): Use this if you are currently on version 10.15.6. 3. Installation Steps
To clean install macOS Catalina 10.15.7 or revive a Mac that has no working operating system, you will need a 16GB or larger USB flash drive and the full installer from . How to download macOS Catalina download macos catalina 10157 dmg file install
Your Mac is too old or too new. Catalina supports: MacBook (2015+), MacBook Air (2012+), MacBook Pro (2012+), Mac mini (2012+), iMac (2012+), Mac Pro (2013+). Fix: Use OpenCore Legacy Patcher (advanced) or downgrade to Mojave. MacBook Air (2012+)
If you need a DMG specifically for deployment (or to mount on a different Mac), you cannot simply zip the .app . You must create a writable disk image. MacBook Pro (2012+)