Thank you for taking the time to report this issue to the Community, although I apologize that you have not yet received a response.
If you are still needing assistance with the CC-502 error with Founders Federal Credit Union, please take a moment and review the information available here.
If the trouble persists after completing these steps, please contact support directly for advanced troubleshooting steps and a review of the logs for possible escalation.
https://www.quicken.com/support#contact-support
Thank you,
-Quicken Tyka
In case of CC-501, 502, 503, 506 errors from a single bank deactivate all accounts with this bank using the same bank logon ID, including any old, long closed, hidden and forgotten accounts that might still be activated. If you miss one, the aggregation server involved in handling Express Web Connect - connected accounts will not start with a clean slate and you will continue to have problems. When done deactivating, restart Quicken and reactivate accounts.