Did you enter the Illinois State return and get to the point where the program says "Here's the income that Illinois handles differently." ?
At that point you should be able to go to the EDUCATION section and then select "College savings and prepaid tuition plan contributions" START
There is no place for College savings contributions. I have been trying to find it literally for 2 hours. I had a contribution last year too so I thought it would reflect it somewhere but I don't see it anywhere. I have clicked everywhere imaginable on both returns and I don't see where I add it anywhere.
Yes, you just have to go through the program answering questions until you reach the income that is handled differently.
I have the windows desktop version - I could not find IL 529 contribution location - I could not get to what you have mentioned.