Our goal, when you're delivering to an apartment complex, is to speed you to the right building, the right hallway, and the right door, period. This is especially helpful at night, when building and apartment numbers are difficult to see.
The help link at Home Page Search tells you how to search for apartment properties. Just remember that all apartment numbers and nearby streets are searchable. That means, when you enter a street or an apartment number in the search field, if it's associated with one of the apartments included for you, that apartment will show up in the search results.
Using Apartment Maps web site like an app
This web site is not distributed as an app. But it's very simple to place a shortcut for it on the homescreen of your phone. That will allow you to open it with one touch, just like an app.