There are several reasons why you might want to download a save game on your PS4:
Ensure you are signed into the same PSN account that originally created the save. Data cannot be transferred between different accounts.
⚠️ Downloading another player’s 100% save often disables trophies for that game. Use at your own risk.
If you have backed up your own progress to the cloud (via PlayStation Plus) or an external drive, you can easily restore it through the system settings.
: To create a comprehensive "paper trail" of your entire console's data, use the Back Up and Restore utility under Settings > System PS5 Transfer
If you answered to all, proceed with confidence. If not, stick to official cloud or USB backups.