Unfortunately the ChargeUp Pro does not support pass through charging.
The fastest way to charge an iPad or iPhone would be to use a lightning to USB-C cable (which is only available to be purchased from Apple). If you are not able to get your hands on one of these cables, the fastest way would be a standard lightning cable plugged into the blue coloured USB-A port.
The fastest way to recharge the powerbank would be with a USB-C to USB-C cord that is plugged into a wall outlet.
Kind Regards, George Santoro Customer Service Team