This sounds like an issue with the shipping company to me, not Apple's fault, so you'll have to talk to the shipping company. There's no way to know what the problem might have been. Perhaps the company tried to deliver but there was not one there to receive the package. Or perhaps they're just behind. The only way to know is to call the shipping company.
It's always risky, no matter who you are buying from, to order and count on a delivery being made on a specific day. There are too many things that can go wrong and very few companies can guarantee delivery.