Worked example
A fulfillment team proofs BOX-101 and BOX-102 on ordinary paper, scans both labels, and only then prints on adhesive stock.
Before you print
Keep the white quiet zones intact. Browser print scaling and printer tolerances can shift bars, so test the output on the intended printer.
Barcode artwork is not proof of an assigned GS1 number. A free barcode image and a GS1-issued GTIN are different things.