Where can I find an ZK Teco SDK for Android?

everyone. I 'm developing an app for Android which makes use of fingerprint readers of ZK Teco. (LIVE20R) I already purchased the device but I can't find an SDK for Android anywhere. It is written on the package that they provide SDK for Windows, Linux and Android free.

So I ask for help here. If anyone has past experience in ZK machines for Android or anyone can find an SDK on the internet, I'll appreciate it.