Puzzle Maker Pro selects Arial as the default font to use for puzzles and puzzle books. A very relevant question is: Can you sell puzzle books where you use Arial to print all the letters and numbers?
Microsoft has a F.A.Q. section about this: https://docs.microsoft.com/en-us/typography/fonts/font-faq.
Long story short: You can use Arial in your puzzle books "Unless you are using an application that is specifically licensed for home, student, or non-commercial use, we do not restrict you from selling the things you print and make using the Windows-supplied fonts"
If you choose to use another font, always check with the creator of the font (Microsoft, for most standard fonts) if you have the right to publish books with this font.