1. If you have sound/music, it must be put into the PP slideshow with the "Animations" facility (not as "Insert"). And that requires a WAV file. Anything else will not show upstream.
Note: The WAV files are huge. Whereas your whole PP slideshow may be 3 to 4 MBs, inserting a music WAV file may add 40MBs to it. But there is a way to make PP accept a MP3 file which is only about 10% of a WAV file. See here for detail.
2. Once your PP show is uploaded, you can have it convertd to an MP4 movie which you can download.
That's all there is to know. I have uploaded this or this one. You can check them out regarding quality (set to full screen).