GetUserName.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using System;

#if (!UNITY_EDITOR)
using Windows.System;
using Windows.UI.Core;
#endif

public class GetUserName : MonoBehaviour
{
    private Text username;

    void Start()
    {
        username = gameObject.GetComponent<Text>();
        FindUsers();
    }

    //function to pull current username
#if (!UNITY_EDITOR)
    public async void FindUsers()
    {
        // リモートユーザー取得
        username.text +=  ("Start Find Remote User\n");

        var users = await User.FindAllAsync(UserType.RemoteUser);
        foreach (var user in users)
        {
            var properties = await user.GetPropertiesAsync(new string[] { KnownUserProperties.AccountName });
            foreach (var propertie in properties)
            {
                username.text +=  propertie.Value + "\n";
            }
        }

        // ローカルユーザー取得
        username.text +=  ("Start Find Local User\n");

        users = await User.FindAllAsync(UserType.LocalUser);
        foreach (var user in users)
        {
            var properties = await user.GetPropertiesAsync(new string[] { KnownUserProperties.AccountName });
            foreach (var propertie in properties)
            {
                username.text += propertie.Value + "\n";
            }
        }
    }
#else
    void FindUsers()
    {
        username.text = System.Environment.UserName;
    }
#endif
}