Kelly,
"Quotas" are set by your school so it could be about anything. By default the quota for an individual course is 500 MB, but at my school we've upped that to 1500 MB. Admins can also up the quota for individual courses. You can see what the quota is set to on your course by going to Settings, Course Details.
Another option that I prefer is to have your students convert the narrated powerpoints to video format. As a powerpoint file the narrations will only be able to be heard by downloading the file AND having powerpoint on your computer. If it's just you that fine, but for like discussions or cases where these are being shared with the entire class it means that they must have a Windows or Macintosh computer with Powerpoint installed. Chromebooks, iPads and mobile phones will not be able to access the audio.
It's super simple to export Powerpoint files to mp4 format from both Windows and Macintosh computers. Generally you click on File, Export and then choose where to save it. Then instead of having the students submit the item as a File in Assignments, have it set to submit Media Recordings. Media recordings do NOT count against your course quotas and will be easier to view on about any device. Students submit the assignments like this How do I submit a media file as an assignment submission? If this is being done as a Discussion so students can all see each others posts then here is how to upload the file in the Rich Content Editor https://community.canvaslms.com/docs/DOC-10623-how-do-i-upload-a-video-using-the-rich-content-editor...
Rick
