The remote server returned an error: (429). during exporting to SharePoint
SharePoint Online uses throttling to maintain the optimal performance and reliability of the SharePoint Online service.
HTTP 429 indicates the calling application sent too many requests in a time window and exceeded a predetermined limit.
The solution here is to upgrade to ABBYY FlexiCapture 12 Release 4 Update 2 or later as it has OAuth authorization via Microsoft services instead of explicitly entering your SharePoint login name and password. This functionality is based on Token Management Service, a service that stores and automatically updates tokens and allow you to bypass SharePoint throttling.
You can download the latest version of ABBYY FlexiCapture 12 via the links: