"The code execution cannot proceed because UnityPlayer.dll was not found." I think you may have left out some files needed for the game to work.
Viewing post in LOST jam comments
From the main page of the game jam:
"Game files are not locked so if you discover a major issue with your game file it is possible to change this afterwards, just make sure you make a submission before the deadline. This is only for game-breaking issues, don't use this feature to otherwise update your game before the rating period is over."
I would consider this a game breaking issue if you wanted to try and upload the entire zip :)