It will have a big impact on what the game feels like to play, and on your ratings, but you can still submit it without it. I'd recommend finding a fitting public domain music track at least if you don't have to add sound effects. If you want to know where to look for them, there's freesound.org and opengamart.org. When looking for stuff, check the "CC0" or "Creative Commons 0" box. It's of course nice to credit what ever music or SFX you use, but you're not forced to.

Looking at your game, I don't think it can make much difference, just the sound of a notification but nothing else, I don't see it as bad.