You already have your visa and do not need to get another one on arrival. There is no need to join the visa on arrival queue at your “port of entry” (e.g. Bali or Jakarta airports). Proceed directly to the immigration desks.
Please be sure to inform the Immigration Officer that you have a Social Cultural visa in your passport so as to ensure that you receive the correct entry stamp. Some Garuda Indonesia international routes include inflight immigration processing. You will be given a coloured landing card when exiting the plane that allows you to proceed directly through immigration.