Name your batch, print the sheet: eight 4×2-inch labels, true size, each with a sample QR that opens the demo batch sheet. In the app, each label’s QR holds that batch’s own details as plain text, which any phone camera can read.
The layout is this page’s own, stated plainly: eight 101.6 × 50.8 mm labels (2 across × 4 down) with 4 mm gutters on a Letter sheet. Print on paper and cut along the dashes, or line it up with a label sheet that shares this layout. The 50 mm check bar prints with the sheet — trust the bar, not the printer.