The e-mail comes from itch.io rather than the game's creator directly, so at least there is no indication that your e-mail address has been leaked to them. They are sending the message through itch.io's interface.
Those e-mails should only be sent to buyers/owners of the game in question, though. If you really do not own that product, it looks to me like something is going wrong but you may have to open a support ticket.