No! it is impossible to change a pick up time for group transfer Shuttle bus from hotel.
You booked the group (budget) tipe of transfer. The carrier company calculates the pick up time for each passenger 24-48 hours before the date of transfer and it takes into account needs of all passengers. You must clarify the pick time following the instructions on the voucher.
The exception to this is only the case if you have changed the flight details (flight number, time and/or date). In this case, you need to notify the carrier company about changes by the emergency numbers in your voucher.