Four steps from the document to a paper you can sit, mark and reuse.
A mock exam is only useful if it feels like the real one. That means the same length, the same mix of question types and a clock. The timer here runs per question, so divide the real time allowance by the real question count. A 120 minute paper with 100 questions works out to 72 seconds each, a 60 minute paper with 40 questions to 90 seconds.
The questions come from your document, not from a generic bank, so the mock tests what you actually taught or assigned. The software samples the whole file, which keeps the last chapters from being ignored the way they often are when a person writes a paper by hand at the end of a long evening.
For a sense of what the output looks like for a fixed exam outline, see the PDF to practice test page, which is written for the person taking the test. This page is for the person setting it.