By default, your presentation is set to advance when you click or tap a slide. You can change this so the presentation advances when you click or tap a link or so it advances automatically with no user interaction.
You can also set your presentation to start playing automatically when the Keynote file is opened.
In the Document pane of the Document inspector, choose an option from the Presentation Type pop-up menu in the Document pane:
Normal: Advances when you click or tap a slide.
Links only: Changes slides only when the presenter (or viewer) clicks or taps a link.
Self-Playing: Advances automatically, like a movie, with no interaction needed. Self-playing presentations are useful, for example, in a kiosk setting.