Missing tracking information (less than truckload/full truckload shipments)

Hello,
I use seller central to create shipments to using LTL or FTL into Amazon Fulfillment Center. This is usually ok when I use the partnership LTL in seller central since it auto provided the Amazon Reference Number.
However, there is a certain time I created a shipment in Amazon and select another as the shipper carrier and then booked Amazon Freighter (Freight.Amazon.com) as the carrier. The shipment creation in seller central asked me for a tracking number and I do not know what that number is when I use Amazon Freight. I got a warning from Amazon that I need to put in the tracking number.
in the BOL from Amazon Freight, it has the following numbers in it. Shipper Reference # (this is the number the same as shipment ID in seller central), Order #, BOL/LOAD #, (10 digit number), and Appointment ID (12 digit numbers). What is the tracking number I should provide in seller central shipment? Thanks