sheetreader for Unity (Sheets API v4)

sheetreader.cs

using System;
using System.Collections.Generic;

using Google.Apis.Services;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Sheets.v4;
using Google.Apis.Sheets.v4.Data;


using UnityEngine;

class SheetReader
{
    static private String spreadsheetId = "1vc2kKeLprOJynjUDglqf10ztD7bog";

    static private String serviceAccountID = "[email protected]";
    static private SheetsService service;

    static SheetReader()
    {
        //  Loading private key from resources as a TextAsset
        String key = Resources.Load<TextAsset>("Creds/key").ToString();

        Debug.Log(key);

        // Creating a  ServiceAccountCredential.Initializer
        // ref: https://googleapis.dev/dotnet/Google.Apis.Auth/latest/api/Google.Apis.Auth.OAuth2.ServiceAccountCredential.Initializer.html
        ServiceAccountCredential.Initializer initializer=new ServiceAccountCredential.Initializer(serviceAccountID);
       
        // Getting ServiceAccountCredential from the private key
        // ref: https://googleapis.dev/dotnet/Google.Apis.Auth/latest/api/Google.Apis.Auth.OAuth2.ServiceAccountCredential.html
        ServiceAccountCredential credential = new ServiceAccountCredential(
            initializer.FromPrivateKey(key)
        );

        service = new SheetsService(
            new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential,
            }
        );
    }

    public IList<IList<object>> getSheetRange(String sheetNameAndRange)
    {
        SpreadsheetsResource.ValuesResource.GetRequest request = service.Spreadsheets.Values.Get(spreadsheetId, sheetNameAndRange);

        ValueRange response = request.Execute();
        IList<IList<object>> values = response.Values;
        if (values != null && values.Count > 0)
        {
            return values;
        }
        else
        {
            Debug.Log("No data found.");
            return null;
        }
    }
}

Hi, I followed your YouTube and this code but I get error says:
Request had invalid authentication credentials. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project. [401]
I checked all the steps and it seems that I have a valid key. Do you know what can cause the problem?

I had the same problem, for anyone who has it as well I found the following solution:

var credential = (ServiceAccountCredential)GoogleCredential
                .FromFile(path + "/key.json")
                .CreateScoped(SheetsService.Scope.Spreadsheets)
                .UnderlyingCredential;

_service = new SheetsService(new Google.Apis.Services.BaseClientService.Initializer()
{
    HttpClientInitializer = credential
});

I create the credential the following way and pass it to the SheetsService, and all other code remains unchanged.