Hi fabtique,
Thank you for posting in the Apple Support Communities. I understand you are having problems adding audio to your Keynote slides.
"Video and audio files must be in a format that QuickTime supports on your Mac. If you can’t add or play a video or audio file, try using iMovie, QuickTime Player, or Compressor to convert the file to an MPEG-4 file (with a .m4a filename extension) for audio, or a QuickTime file (with a .mov filename extension) for video."
You'll find this and additional information linked below.
* Add existing video and audio in Keynote on Mac
Cheers!