Error CS0103: The name 'TimeSpan' does not exist in the current context (CS0103) (testingProgram)?

I am trying to create tests in C# with selenium driver in visual studio. I get the following error. Error CS0103: The name 'TimeSpan' does not exist in the current context (CS0103) (testingProgram) ?? I also have a second error displayed in the images provided. The code uses the PageObjectPattern >> https://www.automatetheplanet.com/page-object-pattern/

Btw I am using a mac.

How do I fix this? Can someone try and run the program to see if it is running on their end?? How do I get this program to run successfully?

here is the following code-

using Microsoft.VisualStudio.TestTools.UnitTesting;
using OpenQA.Selenium;
using OpenQA.Selenium.Firefox;
using OpenQA.Selenium.Support;
using OpenQA.Selenium.Support.UI;

[TestClass]
public class SearchEngineTests
{
    public IWebDriver Driver { get; set; }
    public WebDriverWait Wait { get; set; }

    [TestInitialize]
    public void SetupTest()
    {
        this.Driver = new FirefoxDriver();
        this.Wait = new WebDriverWait(this.Driver, TimeSpan.FromSeconds(30));
    }

    [TestCleanup]
    public void TeardownTest()
    {
        this.Driver.Quit();
    }

    [TestMethod]
    public void SearchTextInSearchEngine_First()
    {
        SearchEngineMainPage searchEngineMainPage = new SearchEngineMainPage(this.Driver);
        searchEngineMainPage.Navigate();
        searchEngineMainPage.Search("Automate The Planet");
        searchEngineMainPage.ValidateResultsCount("264,000 RESULTS");
    }
}

here is the second file-

using Microsoft.VisualStudio.TestTools.UnitTesting;
using OpenQA.Selenium;
using OpenQA.Selenium.Firefox;
using OpenQA.Selenium.Support;
using OpenQA.Selenium.Support.UI;

[TestClass]
public class SearchEngineTests
{
    public IWebDriver Driver { get; set; }
    public WebDriverWait Wait { get; set; }

    [TestInitialize]
    public void SetupTest()
    {
        this.Driver = new FirefoxDriver();
        this.Wait = new WebDriverWait(this.Driver, TimeSpan.FromSeconds(30));
    }

    [TestCleanup]
    public void TeardownTest()
    {
        this.Driver.Quit();
    }

    [TestMethod]
    public void SearchTextInSearchEngine_First()
    {
        SearchEngineMainPage searchEngineMainPage = new SearchEngineMainPage(this.Driver);
        searchEngineMainPage.Navigate();
        searchEngineMainPage.Search("Automate The Planet");
        searchEngineMainPage.ValidateResultsCount("264,000 RESULTS");
    }
}