Most ERP / On Premise Finance systems have a way to bulk-import transactions. Whether this is a simple File > Import or a plug-in for Excel. We can adapt t whatever is possible and recommend keeping it simple. Full integrations can take months and even years to refine or perfect. If you can batch import 20 purchase invoices within 3 or 4 clicks of a mouse, our recommendation is to follow this approach.
On on=premise tool, SmartSync, can be set to receive an invoice payload locally or from the cloud and then release a CSV / XML / JSON file into a location of your choice. Our configurator means we can set the file format to be exactly the way you need it. This means minimal consultancy to install and configure the tools we have. Our proposal will be in hours - not weeks.