Since "RK322xBox" is a generic motherboard name used by many manufacturers, there isn't one single official website. Instead, you must rely on community archives.

If you are looking for better performance, you can try Armbian or LibreELEC tailored for the RK322x chipset on the Armbian Forums or LibreELEC Forum . Flashing Guide (Step-by-Step)

A correct file might be named: RK3229_7.1.2_NHG47K_SSV6051_2GB_16GB_20171214.img

To install the NHG47K firmware, you cannot just copy the file to a USB. You need specific tools.

[Insert download link]