Fill it in, print it or save it as a PDF. Nothing to sign up for.
A till roll is not a small A4 page — on 80 mm the invoice drops to one column with no margins, because that is what fits.
The greyed-out ones come with a TERP workspace, which is also free — they are the reason to make one, not a trap. You get your invoice either way.
Leave a number and we will send you the file and nothing else unless you ask. Skip this and you still get your invoice — the button works either way.