I think, first you have to drive a bit, at least for a week. Then -- you get what you get, maybe uber sends you an email with incentives. You might be offered incentives/guarantees -- but you might not, too.
There's no application. You can email support of course and ask -- good luck with that.
Better get used to the idea of serving the overlord, bending over and asking for lube -- if you're lucky.:confused: