The system for handing out awards is run when Leadership has a chance to do so; it's not automatic. It should show up within a few days or so at the very most, but rest assured, it will arrive. This is the case with most of the ribbons anyway; they are handed out by Division Leaders or above when they get around to it (they do have a lot they handle, and awards aren't necessarily a top priority). And like Ice said, there is no minimum donation required.
Answered, thread locked.