If you can modify the design of the ERP tables, you can add an after Insert trigger to insert a row in a separate table in the ERP database. Of course, there would be no way to identify the engineer unless the ERP already does that.
At a practical level, you most likely cannot modify anything in the ERP database and that would mean that you would need to do this process from Access. I would keep a table with a date and time and use that to select all sales orders entered after that date/time or use a DMax() on a form to find this value from YOUR local table. Then add a new row to the log table when you are done and append the highest date/time you selected from orders. If your sales order table does not include a date/time, you can use sales order ID instead assuming it is assigned sequentially. You don't need a find unmatched. That will get time consuming since it will require joining your ACE table to the ERP database. Doable but slow. Using a query to find the Max() sales order ID (or Date/time) in your Access table, will let you create an append query that selects sales orders higher than the last one in your ACE table.