Downpayments differ depending on various factors such as your residential status and if you bought a house previously.
In late 2019, it was announced that locals and first-time buyers are capable of paying down payments as low as 10% to a maximum of HKD 8 million.
Non-resident foreigners, on the other hand, must pay down payments of around 40% to 50%. For more information, we recommend you to contact local Hong Kong banks directly.