I finally was able to upload my demo. As I mentioned in another thread, I had to split it in seven zip files because the website was rejecting it for some strange reason without any kind of warning message.
I downloaded them again to check their integrity and are fine.
Regardless, I would appreciate to see some confirmation that the seven files are successfully uploaded (i.e. displayed in the website as you can see it), and that split-zipped files are fine for the contest.