I purchased the game but why cant i download it please help
Mahou Mating is only available for pre-order right now. It isn't finished, and isn't available for download.
If you paid for Mahou Mating, didn't realize it was a pre-order, and no longer want it, you can ask Itch.io for a refund. See: https://itch.io/docs/legal/terms#refunds