Connect ShipStation to Quickbooks Online via Pabbly (or Zapier)

I need my ShipStation new orders to be transferred as invoices or sales receipts to Quickbooks online. I have both Zapier and Pabbly accounts but would prefer Pabbly since it has more options on its free plan whereas Zapier considers Quickbooks as a "Premium" app. I understand this procedure quite well and have successfully set up many integrations in the past, but for some reason both Quickbooks and ShipStation appear to have hidden mapping fields or I am mapping the wrong fields. Both Zapier and Pabbly give me errors no matter what I do and I can work out what is causing the error. I need someone who knows their way around Quickbooks, ShipStation and Pabbly (or Zapier as second option) to debug and get this properly set up for me.