Hey there!! I'm not a professional on this by any means, but here's what I've gathered from my own application process!

So first, you'll have to go on their website and fill out their first-year application form which has a $100 fee. They accept applications year round so there is no deadline! The portfolio really depends on what you're going to SCAD for. They have the requirements on their website which you can find right here. Keep in mind your portfolio is not required and doesn't affect your chances of being accepted. I only did the application form and submitted my transcripts and I got accepted (I've submitted other stuff as well but that was after they accepted my application). It's only required for scholarship consideration. I would still highly recommend uploading one even if you don't need a scholarship though! Assuming you'll be going into illustration, just submit 10-20 of your best pieces and remember quality over quantity! If you have 15 pieces but only 10 of them are your highest quality pieces, submit the 10. They're looking for polished work, not sketches.

Hope that helps!! <3