Did you watch it? I just watched the highlights. Here's what I saw:
Disallowed goal: Donnarumma flaps at it badly and gets lucky - pretty soft foul in my view - needs to be stronger.
Goal 1 - Comical own goal - Donnarumma does nothing wrong.
Goal 2 - Fantastic strike - no chance
Save - Great double save around 75 mins to keep it at 3-2
Goal 3 - Another comical own goal - no chance and does nothing wrong
Goal 4 - Defenders allow two free headers in the box from an inswinging free kick, which makes him look like he's in no-man's land. I could be very critical and say he should come for the initial ball, but I think he's got to trust his defenders there, because it's not really central enough for him to be confident of getting there.
Other than that, a few fairly routine saves on the highlights I saw, but no spills and decent handling every time.
Honestly, if we ignore the first disallowed goal, I'd say it's a very unkind reading of the game to suggest he struggled. Obviously any keeper letting in 4 is going to be furious, but none of them were his fault in my book.