landing visa for 2 days in Shenzhen.

We are from Guam, we intend to entry Shenzhen for 2 days visit via Huangqang port , it's not our first time entry Shenzhen for the past 5 years. Are we able to obtain the landing one at the port this time with a valid passport? How long does it take and what should we bring with us beside the passport? What's the fee?your prompt response will be appreciated.