I applied 4 months back, so NOT DEAD SURE about each item.
Bear in mind that you can attach only single file to each section. So, if you want to attach multiple documents to any section. You can join them all in a PDF making sure that PDF's size doesn't cross 4MB limit.
I attached all the property docs, sponsorship affidavit, bank statement and finance related docs in the FINANCES SECTION.
and my IELTS score, all the degrees, SOP, experience letter and other related documents in EXPLANATION LETTER SECTION.