The $500 holding deposit you paid to book your unit will not be charged to your account. The charge is only a hold that will show as pending on your account for 7 days. After those 7 days, the pending charge will automatically be removed from your account.
The $500 charge will not be applied to your rent balance or security deposit.
If you choose to cancel 48 hours after your booking then the $500 deposit is charged to your card and paid to the landlord for the cancellation fee.