Auto save and return for form

I have a very long multipage form, and I’d like to know how to auto save the users inputs and return it for next time they go on the site without them having to click anything. I don’t want them to have to sign in either. I understand wix storage can help but I would appreciate the code for this and how to return the data onload of the page. Addditionally, I’d like it if when they return to the website, it remembers which slide (section of the form) they were on and bring them back to that slide.