I think that is spelled out in context in the previous and next sentences:
snip
”Once a guest puts themselves on the standby list for a Cruise, they cannot be removed from it, and if such guest clears it, their full charge will remain (regardless of whether the guest actually sails on Cruise). If HAL does not confirm guest on the Cruise’s standby list at two (2) days prior to the Cruise’s depart have two options. They can choose to have their reservation cancelled and will be refunded the full amount of the cruise fare that they were charged at the time they were placed on the standby list or they will have the option to remain on the Cruise’s standby list until 90 minutes prior to departure and their booking will be fully refundable if they do not sail. Guests wanting the ability to remove themselves/not be charged for the Cruise if they elect not to sail should instead opt to go on a cruise waitlist (and pay at prevailing rates), not this non-refundable Program“