The document viewer doesn’t display animations from uploaded PowerPoint documents.
There are, however, three alternatives.
Host the presentation
Save as a video
You can export the Powerpoint file as a video, then add the video to the course.
See also: Use Screencast-O-Matic for content creation.
Convert into a Genially
You can convert a PowerPoint document into a Genially, then add the embed code to the course.