How to print: open the resulting PDF and print double-sided
(flip on short edge) at 100 % scale, no shrink-to-fit.
For A5 booklet fold the printed stack in half β for longer booklets, fold each gathering of sheets together rather than the whole stack at once.
For A5 booklet 2-on-1 cut every A4 down the middle and you have two A5 booklet stacks ready to staple β no folding needed.