Inserts the name of the person who created the document here as a field. The field applies the entry made under LibreOffice - PreferencesTools - Options - LibreOffice - User data.
Inserts the page number into the current slide or page. If you want to add a page number to every slide, choose View - Master Slide and insert the page number field. To change the number format, choose SlidePage - Properties - Page tab and then select a format from the list in the Layout Settings area.