Game Foundation: C# "using" namespace error

Hi! I’m trying out Game Foundation and I want to save all the changes that are made in Runtime. So I found this code in the official tutorial:

using UnityEngine;
using UnityEngine.GameFoundation;

public class SaveGame : MonoBehaviour
    IDataPersistence localPersistence;

    void Awake()
        // choose what format you want to use
        JsonDataSerializer dataSerializer = new JsonDataSerializer();

        // choose where and how the data is stored
        localPersistence = new LocalPersistence(dataSerializer);

        // tell Game Foundation to initialize using this
        // persistence system. Only call Initialize once per session.

    public void Save()

    public void Load()

But I’m having this problem:
alt text

Any help will be appreciated!

Did you install the package yet?
In the newer versions of Unity, you can do so by Window > Package Manager > Unity Registry, then search Game Foundation (make sure that preview packages are turned on under the “Advanced” drop down menu).