LEED references ASHRAE 90.1, different vintages depending on the version/scheme of LEED you're using. I suggest you get a copy of the specific version you need, for example ASHRAE 90.1-2010 (LEED BD+C: Retail | v4 uses it)

But yes, that's one VAV per floor. Don't care if your building has 1 or 100 floors. In 90.1-2010 for example, if you have one floor but your area is still greater than 150,000 ft^2, and you have electric heat in the proposed, your baseline is a System type 8, and you'd only use one for the entire floor (except the exception areas...)

G3.1.1 Baseline HVAC System Type and Description.

HVAC systems in the baseline building design shall be based on usage, number of floors, conditioned floor area, and heating source as specified in Table G3.1.1A and shall conform with the system descriptions in Table G3.1.1B.

For systems 1, 2, 3, and 4, each thermal block shall be modeled with its own HVAC system. For systems 5, 6, 7, 8, 9, and 10 each floor shall be modeled with a separate HVAC system. Floors with identical thermal blocks can be grouped for modeling purposes.

Exceptions: [...]