How to register for AP test in Beijing, China for a US citizen studying temporarily in Beijing?

My kid will be in Beijing, China temporarily for around 10 months to improve his Mandarin during his gap year after graduating from high school but before attending college which already accepted him. He would like to register and take the Chinese language AP exam so he can get credits and transfer these credits to his future college. What is the exact process?

Also, if he wants to get a score of 5 on his AP Chinese language exam, what does AP score of 5 correspond to for HSK (?) certification score? In other words, if you can get HSK score of 5 in Mandarin, can you get an AP score of 5? My kid’s future college gives credits only for AP exam score of 5. Thanks in advance.