I thought they needed to freeze. Chicago is maybe too cold for a pot, but an underground parking facility (is this a parking garage?) wouldn't get much below 55 degrees. I think you need something in the middle at about 25-30 degrees for 16 weeks. Naturally, they can take a lot more cold than that if they're in the ground, but a pot is more exposed.
Last year, I had about 500 lilies in my leaf pile (like a cold compost pile) and they were happy as clams. Some were planted and some I just threw in there (in mesh bags to keep the varieties separate). The lily
Society sold them in spring
as a fundraiser.
Do you know anybody with an unheated garage?