RentMaster has for a long time allowed you to create buildings which are a collection of units. A building can be an apartment building or a block of flats or a retail shopping mall or an office building etc. Any property which contains multiple rentable units.
In version 9.9 the process of creating buildings has been made easier. It was made easy with the addition of the Quick Start wizard a few months ago, but this can only be run once. The new Add Building button on the property select list screen will make the creation of buildings easy at any time. The Add Building screen asks for the propertry address etc and the number of units in the building, and automatically creates all the properties required.
You can of course still manually create them all if you wish.