Payment Sync is located under the AutoSync Module and allows you to enable/disable the automatic payment sync.
Automatic Payment Sync: If enabled, payments collected in QuickBooks Online will be automatically synced to ConnectWise PSA based on the time frame you have entered (default is 120 mins). If an error occurs during payment sync the payment will need to be fixed, then the sync will need to be rerun manually for the date range of the failed payment.
Email Notification if Error occurs: If Automatic Payment Sync is enabled, an error email will be sent out notifying of the failure and will include a link that will rerun the payment sync.
See the following article on important information on how Gozynta Mobius handles Payments and Credit Memos.