You must use the Export option to save the slideshow as an MP4 file. You can then burn the file to DVD if all you want to do is play the mp4 on a computer. If you want to play the DVD on a TV via a DVD player, you need to use DVD authoring software. Here are instructions for a free option.
When you use the Save option in the Organizer, it only creates a file that can be opened, edited and saved/exported again in the Organizer. The file is located in a catalog folder location and is not intended to be used outside of Elements.
Using windows 10, also I got it to start exporting this afternoon but stalls at 55% and elements freeze I have to use taskmanger to shut it down when installing 2020 had to get adobe to help it would not install never had a issue before system is amd fx quad core running @3.8 .12 gb ram running. ssd hard drives with 64 bit windows 10 pro it should cope with elements use other hdr editing software and don't have a issue