If you have paid for your stay in full and upfront, you should not receive a request for a pre-authorisation when checking in through Shackle.
Shackle should only request a pre-authorisation for reservations that have been reserved but no payment has been made.
If you are certain that you’ve paid for your stay upfront but you are still seeing a request for a pre-authorisation, please check in at the front desk to avoid the possibility of a double charge.