Yep. Exactly what Arrow said. Since there's no judging or ratings, it's pretty casual. If you want to sell on another platform you can always make a post here to share the link. But it can't hurt to sell in two places at once! Just more traffic for your game!
You could also upload a demo on Itch with a link to the full game, wherever that is hosted. If you have time, of course.
And the deadline is more of a guideline to keep you focused, but if you need an extra week to get your store page up or to add a demo, it's totally fine.