The delivery is made by the restaurant or by a specialized courier company.
Each restaurant determines its own price for delivery, depending on the order value and the remoteness of the restaurant according to the delivery address.
You can see the time for which each restaurant delivers on the top right corner of the its page above the menu. In 90% of the orders, your food will arrive in 50 minutes or less.
You can order Takeout and get your order by yourself straight from the restaurant on your way back home or to the office. In this case, you don't pay a delivery price, but only the value of the ordered food.