name supplied already exists – usually means there is a customer and a vendor with the same name, or there is a PO or invoice under the same exact number (in your QuickBooks account).
Unauthorized-401 – this means that you are not logged in to your QuickBooks Online account. Make sure you're logged in on another tab (in the same web browser as your Hexicom system) and try the export once more.
Invalid Reference Id : Names element id ### not found – this means that the back-end database ID # for the invoice's customer in your Hexicom system is different than the database ID # for that same customer in your QuickBooks Online account. This will happen if you delete a customer in either system and create an entirely new one under the same name. If this is the case, please contact support so that we can change the database ID # for that customer in your Hexicom CRM.