Getting familiar with the LGIM and addressing takes a little time and exploration. We've been working with this a bit and have some more to go, but for simplicity here's what I know so far:
When creating a new address you click on a road centerline first to create the address point, then click on the location that the site address point will be. IF you don't double click then each location you click for a site address point will have the same address point number and related address point ID, then you can separately address each site address point with unit type and number. I've included a screen shot to help illustrate. To take this further, if you had building footprints and facility polygons you would also transfer information to these address sites such as if this site were called "Example Commons".
Jacyln - The Address Data Management solution does support multi-unit dwellings. Fundamentally, it assumes that each site address point is a unique address. Then you can specify a unit type/unit designation as well as an alternate unit/type/unit designation. Steve's example above is a great illustration. Hope this helps and let me know if you have any questions.
One more note on multi-units. We are wrapping up some enhancements to the addressing tools for our June release. Among others, these enhancements will allow you to auto-increment address numbers in situations like this.
Finally - if you are going to the UC this year, we have a TW that will dive deeply in to our Addressing Solutions.