https://www.reddit.com/r/oculus/comments/1jw8ao/protip_for_unity_devs_here_single_file_executable/
This may be helpful, I remember my first time packing and building a game was pretty hectic, make sure that you get ALL the files that unity creates when you export your game, not just the exe file (you need the crash handler and the dll file as well). The tutorial above shows you how to pack all of those files into a single runnable exe so uploading to itch is ez.