To tendo erros em todas as aulas praticamente

Consegui resolver, estou usando .NET5 e de acordo com essa versão, estava faltando algumas implementações na classe startup do projeto Auth.Provider que ficou assim:

OBS: A parte do swagger coloquei opcional. Estava tendo problemas de rota entao foi necessario acrescentar o app.UseRouting();

        app.UseAuthorization();

using Alura.ListaLeitura.Seguranca;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace AluraWeAPI.AuthProvider
{
    public class Startup
    {
        public IConfiguration Configuration { get; }

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

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<AuthDbContext>(options =>
            {
                options.UseSqlServer(Configuration.GetConnectionString("AuthDB"));
            });

            services.AddIdentity<Usuario, IdentityRole>(options =>
            {
                options.Password.RequiredLength = 3;
                options.Password.RequireNonAlphanumeric = false;
                options.Password.RequireUppercase = false;
                options.Password.RequireLowercase = false;
            }).AddEntityFrameworkStores<AuthDbContext>();

            services.AddControllers();
            services.AddMvc();
            // Register the Swagger generator, defining 1 or more Swagger documents
            services.AddSwaggerGen();
        }

        // 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();
                app.UseSwagger();

                app.UseSwaggerUI(options =>
                {
                    options.SwaggerEndpoint("/swagger/v1/swagger.json", "v1");
                    options.RoutePrefix = string.Empty;
                });
            }

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}