You can’t checkmate with just a king, therefore it will be a draw due to insufficient material. I remember when it happened to me for the first time, I was confused. But basically, if you don’t have sufficient enough material to checkmate your opponent and the clock time runs out, it will be a draw.
I know I was low on time so I was making pre-moves. But as soon as white moved, it's a draw.
What have I done wrong? Can't I win with these material?