Compare the output to Apple’s official SHA-256 hash for Catalina 10.15.7 (Build 19H15). A legitimate hash will look similar to: 1320c9d7e91cda967fe2845bc02117aa5bff2d706c2c3e6f0b93f6ac601a430b (Always check the latest hash from Apple’s security pages)
rather than a single direct-download DMG file from a support page. The Quest for a Verified Installer
Here is the safest way to get the Catalina DMG and how to verify it.
The quest for a source ends here. Do not trust random websites. Stick to Apple’s CDN via the softwareupdate Terminal command, always verify the SHA hash, and use the createinstallmedia method for bootable drives.
softwareupdate --fetch-full-installer --full-installer-version 10.15 Apple Support Updates : Apple provides manual DMG downloads for update patches
