I've never installed it, but I've thought about it over the years several times.
My understanding is that you need to get the floor cleaned down to bare concrete. So no oil drips, no tire marks, and ideally no divots where the construction crew nailed in supports when they were building your house.
The one thing you might want to consider is adding some sand to the paint for traction (which will require a 2nd kit to have enough paint). The paint by itself will be very slippery when wet or oily.
Chip H.