I have a large book in which 1 PDF page contains 4 pages from the book. Is there a way I can crop those pages and put them in order without doing it manually?
Yes. You can do it manually using the Crop Pages tool (under Tools - Pages), or it can be done using a script (more complex but faster and more reliable).
Thank you. I don't want to do them manually because it is a book with over 500 pages. Do I have to create the script or is there one already created? Any help would be greatly appreciated.
Well, I've developed a script that can split each page in two (either horizontally or vertically) and then re-combine them into a new file (Custom-made Adobe Scripts: Acrobat -- Split Pages in 2 Parts and Combine to a New File), so it should not be too difficult to adjust it to do what you've described. You can contact me privately (try6767 at gmail.com) and we could discuss the details.