How can I use Auth0 with .net core API and Angular?

My problematic

I'm trying to make a basic login page with Angular and asp.net core using Auth0 and I have no idea of how all this is working... I try to test my API before connecting it to Angular with Postman and every time I get a Bearer error="invalid_token" on postman even if I use the good token.

Also

The documentation example only returns a message "Hello world" with the Controller (Api endpoint) and I don't even know what I am supposed to put thereafter to connect my controller and Angular service together, I'm sooo lost in all that codes...

Here is the documentation I'm looking for .net core, Angular, and then to test the API with Postman.

Please help me, thanks for the future answers!

My appsettings.json

  "Auth0": {
    "Domain": "dev-icv0769a.us.auth0.com",
    "ApiIdentifier": "https://localhost:44398/api/Login/private"
  }

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.AddControllersWithViews();
            // In production, the Angular files will be served from this directory
            services.AddSpaStaticFiles(configuration =>
            {
                configuration.RootPath = "ClientApp/dist";
            });

            services.AddDbContext<CLDbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

            string domain = $"https://{Configuration["Auth0:Domain"]}/";
            services.AddAuthentication(options =>
            {
                options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
                options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
            }).AddJwtBearer(options =>
            {
                options.Authority = domain;
                options.Audience = Configuration["Auth0:ApiIdentifier"];
                options.TokenValidationParameters = new TokenValidationParameters
                {
                    NameClaimType = ClaimTypes.NameIdentifier
                };
            });

            services.AddAuthorization(options =>
            {
                options.AddPolicy("read:messages", policy => policy.Requirements.Add(new HasScopeRequirement("read:messages", domain)));
            });

            // register the scope authorization handler
            services.AddSingleton<IAuthorizationHandler, HasScopeHandler>();

        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            if (!env.IsDevelopment())
            {
                app.UseSpaStaticFiles();
            }

            app.UseRouting();
            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller}/{action=Index}/{id?}");
            });

            app.UseSpa(spa =>
            {
                // To learn more about options for serving an Angular SPA from ASP.NET Core,
                // see https://go.microsoft.com/fwlink/?linkid=864501

                spa.Options.SourcePath = "ClientApp";

                if (env.IsDevelopment())
                {
                    spa.UseAngularCliServer(npmScript: "start");
                }
            });
        }
    }

My LoginController.cs

   [Route("api/[controller]")]
    [ApiController]
    public class LoginController : ControllerBase
    {

        [HttpGet]
        [Route("private")]
        [Authorize]
        public IActionResult Private()
        {
            return Ok(new
            {
                Message = "Hello from a private endpoint! You need to be authenticated to see this."
            });
        }

        [HttpGet("public")]
        public IActionResult Public()
        {
            return Ok(new
            {
                Message = "Hello from a public endpoint! You don't need to be authenticated to see this."
            });
        }

    }

NOTE: I also have HasScopeHandler and HasScoreRequirement.cs in my solution.

Postman response with the error message

If you need something else to help me, just ask, thanks again!