Hi @KimberlySlatter ,
I don't use MS products much with Canvas, but I believe you have to save the PowerPoint to the cloud in order to do what you are asking. I think the autoplay feature is going to be set within the PowerPoint show and not in Canvas. Once you publish to the cloud, you will need to get the URL for it that you can then place in Canvas (in a Module as an External URL or within the RCE as a link). As far as I know, PPT files can't be embedded in Canvas and have to open in a new tab to display/play as designed.
I think these are the instructions you want:
If you include the PPT in its native format (not the web version), your users will have to have PowerPoint installed and will have to download the file and open it in their own program.