Could not create article with title '' because it does not have a product number.
The integration is trying to find or create a product in SnelStart, but cannot find it.
Make sure that the articles in your source package have a product number.
You may have configured the integration incorrectly. Is it possible that you have set the integration to create Sales Invoices and set the 'Create Articles?' setting to NO? If so, change this step to YES. In order to create a Sales Invoice, a product needs to be created (or looked up) in SnelStart.
If you only want to use the financial integration, set the integration to Sales Bookings. Then, no articles need to be sent to SnelStart and the 'Create Articles?' step can remain as NO.