Spray it on with a spray pump, wait 5-10 minutes, rinse off with a garden hose.

Spray the floors with that and the urine crystals should break down.

There is often damage below roof valleys.Damage at trim (usually from failed sealant).Damage from miss directed from sprinklers (years of direct spray can affect many exterior wall coverings).  

I will spray paint the fridge. 

From what I understand treatments used in older homes last decades, but the sprays used in new homes only last about 7 years.  

I laugh because one property we looked at wreaked of cat spray and feces.  

In FL we used to spray bi-monthly for ants.

It is like using spray paint to paint you car.

There is insulation on the underside of the concrete roof slab (confirmed from inside one of the units - so given that, I would not be surprised if they also sprayed the top of it, or laid down a membrane, for waterproofing before putting down the shingles.

Go over with a spray bottle filled with hydrogen peroxide and water or bleach and water (the hydrogen peroxide is better at permanently dealing with the issue), spray, wait, show them it's gone.