The instructions on this page are clearly out-of-date: https://www.hamrick.com/vuescan/html/vuesc4.htm.
For one thing, there is NO tick box for "PDF multi page" It's a pop-up choice list.
Scan does NOT work. Preview does.
There is NO "Last Page" option on the File menu.
The screen shots are from Windows, but I can live with that.
This used to work for me. Not only was there a Last Page option on the file menu, there was a clickable Last Page command at the bottom of the input page. What gives?