That all sounds very strange. What use is the source file to him, and if you paid him to write it, surely you should get it?
You need a DC adapter, not AC. The USB will power the board, but not necessarily what you have connected to it.
... a cool yet expensive project using Arduino.
What project? Your post is so light on details it is almost impossible to advise.
If you paid by credit card I would be reversing the charge, you would reasonably expect it to work, otherwise how do you know he did anything at all?