Delivery takes longer than the estimated time could be 2 reasons;

Order stays " To Be Delivered" for 30min- 1Hour, there's many orders at the moment and the operaters need some time to get them started one by one.

Order stays "Delivering" for longer than estimated time, this could be the system connection is not well, so the delivery is slower than usual, but as long as the status is "Delivering',there is nothing wrong with your order, all you need to do it wait patiently.