Did you not receive anything at all in writing when you handed over this "deposit"?
If it's a holding deposit and your application isn't approved, I believe that you're entitled to its return less any reasonable costs the landlord incurs in putting the unit back on the market.
You may find this link helpful:
http://atg.sd.gov/LinkClick.aspx?fil...8%3D&tabid=525
If you're approved (and I've no idea whether or not you'll be approved) the holding deposit is usually applied to either the security deposit or the first month's rent.
Hope that helps a little. For now just wait and see what happens - good luck!