A signature isn't required for your delivery, but it's ultimately up to your carrier's discretion whether your box can be left alone or not. If there's a specific location you'd like your boxes to be delivered to, you can add delivery instructions in your Account Settings in the Shipping Details section.
Our food is shipped in insulated boxes that should stay cold for several hours upon delivery. But, it's best to unpack and refrigerate your food as soon as possible.