Saved snapchat stories into PP

Hi there! I am trying to turn several saved snapchat stories that I transferred from my iPhone onto Dropbox, then put into Premiere Pro on my Macbook.

First I had an issue where the files were not importing onto the timeline properly. The first one I dragged on would be fine, but the next would all be audio only.
Converting the files into .mp4 resolved that issue, thankfully. I thought that would be my only speedbump, but it turns out I was wrong!

Once I was finished putting the video together, I was ready to save my work! I realized I wasn't sure how to export the video, so I did some research on here and followed many different peoples' advice. I have exported probably about twenty times and each time I watch the final result, it's super glitchy.

Anyone have advice for me? What am I doing wrong? How should I have my export settings for this type of stuff? Should I just edit the snapchat clips on my phone in iMovie instead?