Get up all the oil you possibly can with some kind of degreaser -
like this. Use a stiff bristled push broom type of a brush. You can give the floor a short bath in muriatic acid to score it up for a little better adhesion. Also, make sure you follow whatever the box says for the wait time to park on top of it, last thing you want to do is roll your smoldering hot tires on top of that stuff before it's totally cured and drive away with it still attached to your tires the next day.