MacOS Catalina and Big Sur protect you from malicious code by asking for all Installers to be Notarized as only containing 64-bit code. Big Business includes 32-bit code to connect Old Client, support 32-bit Micosoft Office, and more.
To install on macOS Catalina or macOS Big Sur:
1. Run the installer and click OK for not scanned.
2. Go to Apple menu, System Preferences, Security.
3. Click Open Anyway, then run the installer again.