If the user can't download it from the Mac App Store, they might need to use the "Install macOS Catalina" app via a different method. Some sources suggest using the -seed or developer account options, but that's probably not relevant here. Alternatively, there are third-party tools like UTM or others that bundle macOS ISOs, but I should caution against piracy or illegal downloads.
Catalina is the last macOS to support legacy 32-bit apps before the move to strictly 64-bit architecture [2]. Step 1: Securely Download the macOS Catalina DMG File If the user can't download it from the