Thanks for reaching out deathly_hedgehog,
It sounds like you're having some trouble with looping your presentation in Keynote. We can help.
You can check out the Keynote User Guide for Mac to Make a presentation advance automatically in Keynote on Mac:
You can set your presentation to advance automatically, like a movie, with no interaction needed. You can also set it to play immediately when it’s opened, or to play continuously in a loop.
1. In the Document
sidebar, click the Document tab.
2. Click the Presentation Type pop-up menu, choose Self-Playing.
You can adjust the controls next to Delay to modify the transition or build effects timing.
3. In Slideshow Settings in the sidebar, select any of the following playback options:
- Automatically play upon open: The presentation begins playing immediately after it’s opened.
- Loop slideshow: At the end of the slideshow, the presentation returns to the first slide.
- Restart show if idle for: Use the up or down arrow to set the amount of idle time with no viewer interaction before a presentation returns to the first slide.
4. To play the presentation, click the slide you want to begin with in the slide navigator, then click
in the toolbar.
Hope that helps.
Take care.