A network-related or instance-specific error with C#

I get an error like this:

A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: TCP Provider, error: 40 – Could not open a connection to SQL Server)

Here is my apppsetting.json:

  "DBInfo": 
  {
    "Name": "MySQLconnect",
    "ConnectionString": "server=localhost;user Id=root;password=root;database=cinemapanda4;"
  }

and here is my StartUp.cs:

public class Startup
{
   public Startup(IConfiguration configuration)
   {
      Configuration = configuration;
   }
   public IConfiguration Configuration { get; }

   // This method gets called by the runtime. Use this method to add services to the container.
   public void ConfigureServices(IServiceCollection services)
   {
      services.AddSession();
      services.AddDbContext<MyContext>(options => options.UseSqlServer(Configuration["DBInfo:ConnectionString"]));
      services.AddControllersWithViews();
   }

   // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
   public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
   {
      app.UseDeveloperExceptionPage();
      app.UseStaticFiles();
      app.UseRouting();
      app.UseSession();
      app.UseAuthorization();
      app.UseEndpoints(endpoints => {
         endpoints.MapControllerRoute(
            name: "default",
            pattern: "{controller=Home}/{action=Index}/{id?}");
      });
   }
}

I’m using MacBook and how can I fix this problem?