Printing company wants 300 dpi,but in adobe Illustrator there is 300 ppi

I have already created 96 pages for book with Ai,but there's only 300 ppi option. Printing company wants 300 dpi,what I need to do?pls help.. Do I need to start everything from begining with Photoshop.... And if no. what parametres I should put for exporting pdf?