How to organize authorization through Steein OAuth2 on Android?

Question

Android

Good evening.
Guys, can you tell me how to make authorization through Steein for android, I just couldn’t find the library.
On Github I found only for PHP .
Their official website has documentation on how to implement it, it just takes a lot of time for me to implement it.
No, yes, some ready-made libraries, please, it is very necessary.
Thanks in advance.