Presentations in Express not viewable in Canvas LMS - file size

The "Presentation" type of Express file seems to create unusually large file sizes, to the point that students could not upload a PDF of the Presentation to Canvas LMS as an assignment submission. Recevied this info from an instructor using it for 2 classes of about 30 students each, so plenty of cases of the issue:

"my students and I are having a difficult time trying to load/view their projects in Canvas!  Canvas is saying that the files are too large, or it’s simply truncating their work.  The students who’ve had luck have attached a zip file which means I have to download and view each slide separately. We tried saving the presentation as a Pdf, and jpeg, and neither of those worked.  For now I’ve been able to have the students give me their “adobe” share link so we can use that, but unless we’ve done something major wrong this is a real limitation for trying to use Adobe presentations with Canvas. In that past both power point and canva presentations have loaded successfully into  Canvas, so I’m not sure what the problem is (we tried reducing the image/pixels/file size)"
These Presentations did not contain animation, videos, etc. only static images and they were not long presentations. The standard file size limit for assignment files in Canvas is 500 MB. Saving as PDF should compress the file enough for it to be viewable within Canvas for ease of teacher grading. Yes they can submit a link, but then instructors have to open a new tab to view the work and grade it, or maybe even download as PPT but that defeats the purpose of using Express for Presentation. This was the first time we'd tried using Presentation as an assignment within a class and this is a teacher very eager to use Express, so sad that it turned out this way. We are an Adobe Creative Campus so we are high level users and high functionality with our Canvas LMS is crucial.