Since it's a powerpoint slide deck, each "page" is an independent slide. Unlike a Word document, the text won't auto-paginate. You have to manually put the words you want on each page. (Although you can cut/paste from a slide where there are too many words, it's easiest to copy/paste from your source document.)

To create new pages, just select "New slide" and then from the "Template" drop down, pick the layout you want. Then paste your text into the text box on that slide.