It depends really on the format of the game, I think for a download itch go with a zipped up build file so it self extracts but as long as we can get access to it then any is fine :)
No worries, This Jam was essentially a practise run so nothing too hectic to worry about.
Even if people dont submit its the process of making the game that was the target for this game jam.
Later ones will be a bit more organised (Mainly due to i had a stomach bug and followed by a heavy cold which i am still recovering from)
The main point is just to have fun :)