How do I cancel or get a refund in case of cancellation?
This down-payment is actually being charged, only after the host (landlord) has confirmed the reservation and accepted the booking.
As long as the host has not confirmed your reservation/booking, you are free to cancel the reservation through the cancellation link that can be found on the booking screen. However, once a reservation is confirmed, the down-payment cannot be refunded and you are bound to the cancellation terms that the owner has specified (and are presented to you throughout the booking process).