The definition of highway in Tennessee Code § 55-1-116 is:
"Highway" or "street" means the entire width between boundary lines of every way publicly maintained, when any part thereof is open to the use of the public for purposes of vehicular travel.
The law regarding overtaking buses applies in two circumstances: when the bus is on a highway (which per the above definition essentially means any public road when opened to the public for traffic) or the bus is located on property "owned, operated, or used by a school or educational institution." A private parking lot of an apartment complex is neither one of those.
Of course, should you see the stop sigh and flashing lights of the bus, fail to stop as you would need to do on a highway, and end up hitting a kid as a result, you'll likely be found liable for the injuries the kid suffered as a result, so I would not advise ignoring those warnings from the bus.

