In the Edit Module, choose Add Page Marks -> Page Number: 

Click on the three dots in the right upper corner to open more options:

The Text and Format options will let you decide the format of the numbers on the pages. Here is a description of each section: 

• Position– Choose between 6 possible page positions for your numbers.
• Start At – This determines which page number starts the numbering. For example, you may wish page 1 to start at the actual page 3 of your document. 
• Number Format – Choose from available number formatting options in this dropdown menu. 
• Font –This lets you choose a font from the available list.
• Font Size – Here you can choose how big or small the numbers should be. 

The Pages to apply section will let you choose which pages you want to be numbered. Here is a description of each section: 

• All – This will number all the pages in your document. 
• Current – This will number only the current page. 
• First only – This will number only the first page. 
• Last only – This will number only the last page.
• Range – You can decide a range of pages to be numbered. 

When you select Insert, the page number will be added to your document: 

You can remove page numbers in the Edit Module. Click on Remove Page Marks and then Page Number.

Click on REMOVE.