A visa / entry permit for chinese passport holder

My friend holds a chinese passport. We plan to visit Macau for 2 days for tour, what is the requirements for her? We will be entering from Hong Kong to Macau and will exit to Hong Kong again by ferry. My friend has a mutli-etry permit for HongKong.
Does she need a visa, if so, can it be visa on arrival or should it be pre-applied to chinese consulate? Currently we are in HK (she does not have HK ID)
Thanks.