Namespace GooglePlayGames could not be found

I'll try my best to describe my issue: Using this plugin and following this guide i'm trying to implement google play service on my game, but google's code is written in c# and my game is entirely in js, so i got a lot of problem by accessing them. Then i create a simple c# script that should initialize google play service:

 using GooglePlayGames;
 using GooglePlayGames.BasicApi;
 using UnityEngine.SocialPlatforms;
 
 public class GoogleDialer : MonoBehaviour {
 
     // Use this for initialization
     void Start () {
         GooglePlayGames.Activate();
         Social.localUser.Authenticate(authentication);
     }
     
     void authentication(bool success){
     if (success) print("Logged with: " + Social.localUser.userName + " ID: " + Social.localUser.id + " Underage: " + Social.localUser.underage);
     else print("Not logged");
     }
 
     
     // Update is called once per frame
     void Update () {
     
     }
 }

This script should be run at the start of the game, but by the script it seems that i can't access google's script:

Assets/Plugins/GoogleDialer.cs(1,7): error CS0246: The type or namespace name GooglePlayGames' could not be found. Are you missing a using directive or an assembly reference? Assets/Plugins/GoogleDialer.cs(2,7): error CS0246: The type or namespace name GooglePlayGames' could not be found. Are you missing a using directive or an assembly reference?

I put the c# script in plugins folder because i read that this is the solution to allow js script to access the c# ones I tried almost eveything, scrambling scripts and folders but none has worked, according to the guide this shouldn't happen so i don't know what should i do D=

This is the script i'm trying to access by the code i've wrote, my code is located in:

New Unity Project/Assets/Plugins

Google's code that i'm trying to access is in:

New Unity Project/Assets/GooglePlayGames/ISocialPlatform