The Billing Sync data flow exports invoices/cash sales from NetSuite to Shopify. The data flow exports fully/partially billed orders in NetSuite
Flow Steps
Step 1: Get NetSuite invoices
Get all invoices from NetSuite that are created since the last flow run time.
NetSuite Saved Search fetch invoices from NetSuite (Provide the internal Id of search)
Only modified invoices from NetSuite are imported to Shopify

Step 2: Import Shopify billings
Create payment transaction for the Shopify order by order id.
Operation is creates a transaction for an order
Order id is {{{[Document Number]}}}

Field mapping

save and close. Run the flow.