If you want to create a bootable installer on a USB drive, follow these steps:
Select the option for macOS Catalina 10.15.7 to download the raw component files ( InstallAssistant.pkg ).
diskutil eraseVolume JHFS+ Catalina /Volumes/Catalina macos catalina 10157 iso download new
Once the process is complete, unmount the newly created installer volume.
Create a VDI disk with at least 40GB of storage. If you want to create a bootable installer
Open Terminal ( Command + Space , type "Terminal", and press Enter) and run the following commands sequentially: Step 1: Create a Blank Disk Image
| Red Flag | Why it’s dangerous | |----------|--------------------| | Filesize not ~8.5–9 GB | Too small = fake; too large = bundled malware. | | Password-protected archive | Hides malicious scripts. | | “Cracked” or “Pre-activated” | macOS doesn’t need cracks — it’s free. | | .exe file inside | Windows virus, not a Mac ISO. | | Uploaded this month from an unknown user | Old OS + new upload = bait. | Open Terminal ( Command + Space , type
Change the extension from .cdr to .iso to finalize your copy on your Desktop, then clear out the temporary file left behind in your storage directory:
Use Apple's built-in createinstallmedia tool to extract the Catalina installation files into your mounted image. You will be prompted to enter your Mac’s administrator password:
: hdiutil create -o /tmp/Catalina -size 8500m -volname Catalina -layout SPUD -fs HFS+J
Always verify the checksum of a downloaded ISO. If a website asks you to disable your antivirus or fill out endless surveys to get the file, avoid it. These are often scams or contain adware.