Follow bellow steps for installation
  • Download the package from Package Manager inside Unity

  • Import it in your project

  • Add Google's Game Package Registry for Unity to your project: .

  • After adding Game Package Registry, you should import Google Play Core package to your project from Unity. Open menu Windows -> Package Manager ,from the drop down menu on top left part of the Package Manager windows select 'My Registries' and Install 'Google Play Core'.

  • And that's all, you are good to go!