The door-to-door service means that the courier will do both the collection and delivery at the address you entered during the purchasing flow.
Almost all the services displayed on Packlink are door to door, but there are exceptions that you can check in this article. However, this does not mean that the courier is obliged to go up to a fifth floor without elevator, to pick up or to deliver a parcel. For this reason, remember to leave the goods in an accessible place to simplify the pick up/collection.
In case of shipping bulky goods, please check this article.