Let the school know you're thinking of applying — they can share their prerequisites and help you through the process.
It's best to ask — circumstances can change at any time.
Beijing Aidi School (Beijing Aidi International School) is a K–12 school on the Beijing Aidi International Education Park campus at No.7 Louzizhuang Road in Chaoyang District. The school states it was founded in 1999 and enrols students aged 3–18. The campus houses a range of academic and sports facilities and an international high school offering multiple pathways (IGCSE, A‑level, WACE/Australian high school certificate, AP, BTEC and domestic high‑school programmes); the site notes the school's Australian high school (WACE) has been in place since 2004. The school publishes articles and a feature about student dorm life (student hostels) for senior students and a campus FAQ states it operates a school‑bus service for younger year groups. (All items above are taken from the school website.)