Google Play Game Services Error

I’m using the Google Play Game Services Plugin : GitHub - playgameservices/play-games-plugin-for-unity: Google Play Games plugin for Unity
As I import it and tries to build my project, this error occures:

CommandInvokationFailure: Unable to convert classes into dex format. See the Console for details.
D:/Programmer/Java\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir="D:/Programmer/Android SDK	ools" -Dfile.encoding=UTF8 -jar "D:\Programmer\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar" -

Does anyone know why?

Google Play Game Services are quite picky and buggy in Unity (as most Google products are). Make sure you have the proper SDK tools installed (or reinstall them) and the plugin you’re using is the very latest Google published. Also check if you have other Google plugins such as Admob, having both plugins caused horrific issues for me.

try https://github.com/unity-plugins/google-service-unity
It is more easy.