Corrupted Digital Games

Unfortunately, that won't work.

First, what you're uploading to PS Plus or a USB stick is not the game itself, but your game progress (aka. savegame). Savegames are useless without the game itself.

Second, even if you could upload the entire game to PS Plus or a USB stick, you'd still be uploading the corrupted game. Which means you'd be downloading the same corrupted game back onto your PS4. This won't achieve anything apart from wasting your time.

Your only option is to either have the game owner download the game on your PS4 again, or buy the game on your own account.

However, it appears you don't quite understand the difference between a game and a savegame, so it's unclear whether the game itself is corrupted, or whether your savegame is.

If your savegame is corrupted, you'll have to try loading your earlier savegames until you find one that isn't corrupted. You won't need to gain access to the owner's account or buy the game for yourself. In the worst case (if none of your savegames are uncorrupted), you'll have to start a new game.

Your PS4 might have automatically deleted older savegames to make space for newer ones. If you're lucky, you can fetch older savegames from PS Plus, if they haven't been deleted from there yet. Fetching savegames from PS Plus may delete the savegames on your PS4, so I'd recommend making a backup of your current savegames to a USB stick before messing with PS Plus, just in case.