File management & downloading through PLEX sync - How does it work?

So my brother was syncing some of my shows to his iPad when he got a message saying my server’s disk was almost full. I understand that PLEX needs to transcode the files into optimized versions which takes up space, but what happens after?

Does PLEX delete the optimized versions as soon as the download is complete? When I check my server, both the “Optimized Versions” and “Conversion Log” pages are empty, even though his iPad is still attempting to download videos.

Will canceling a download delete the temporary file on my server to allow other videos to be downloaded?

PMS transcodes the video to the best format for the sync client, then stores that video file on your server (if you have a look in your server settings it will tell you where, but by default this will be in a new folder with the original media). It keeps this copy there