error CS0118: 'SocketIO' is a namespace but is used like a type

[Mathiaszero]

using System;
using System.Threading.Tasks;
using System.Text;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Connection: MonoBehaviour
{
    void Start()
    {
        var client = new SocketIO("http://localhost:11000/");
    }

    void Update()
    {

    }
}

How can I resolve?