I am having the same problem (CC-502) error with my Synchrony Verizon Visa account. No transaction downloads and then CC-502 error when trying to reset the online connection. Running Quicken Premier Subscription R42.8 on Windows 10 Home. Also my Synchrony Sam's Club Visa has the same download problem. Both are using "Synchrony Bank Credit Cards" as the Financial Institution
I followed the instructions with my Synchrony Sam's Club credit card account. The update behaved normally but no transactions were downloaded. I had to manually export the transactions from Synchrony to Quicken.