Sorry, my mistake. I thought the quarantine message appears earlier. It appears at the latest possible moment - after you decided how much money to give and when pressing the red download button on the actual file.
But if you were not formally notified about a quarantine, I would still just ignore it and operate the page normally. I have seen that happen to another established account some time ago. Half the games were suddenly quarantined. I believe in that case accessing the games with a vpn might have been the cause: Itch might have thought the account was hacked.