I'm pretty certain that this was answered on the jam page.
"8. I'm accepting late entries until 24 hours after the end of the submission period. In order to submit late, first publish your game to itch, and then send me the link, either on Discord or in the Community tab. Uploads will also be unlocked, so if you have a bug fix to publish, do it during this time!"
Personally, I have the same issue of "I need 1 more day". I am SO GLAD that they allow submissions up to 1 day late. Honestly, I think It's main purpose is for games that suddenly stop working when put through itch.io so the devs will have a chance to fix it, or for people like us so that we can sleep on the last day of the jam if we fall a little bit behind schedule.