Can anyone explain why my game ended in a draw?

You can only win on time if you have enough material to get a checkmate. Since you won on time but had only a king, it was a draw. If you had a pawn, you would have won.
You can only win on time if you have enough material to get a checkmate. Since you won on time but had only a king, it was a draw. If you had a pawn, you would have won.