public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        // add your authorization provider (asp.net identity, identity server, whichever..)
    
        services
            .AddControllersWithViews()
            .AddMvcLocalization();
    
        services.AddRazorPages();
        services.AddRouting();
    
        services.AddDbLocalizationProvider(_ =>
        {
            _.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
            ...
        });
    
        services.AddDbLocalizationProviderAdminUI(_ =>
        {
            ...
        });
    }

    ...
}

public class Startup
{
    ...

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseRouting();
        app.UseAuthentication();
        app.UseAuthorization();
    
        app.UseDbLocalizationProvider();
        app.UseDbLocalizationProviderAdminUI();
        app.UseDbLocalizationClientsideProvider(); //assuming that you like also Javascript
    
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapRazorPages();
            endpoints.MapDbLocalizationAdminUI();
            endpoints.MapDbLocalizationClientsideProvider();
        });
    }
}

using System.Collections.Generic;
using System.Globalization;
using DbLocalizationProvider.AdminUI.AspNetCore;
using DbLocalizationProvider.AdminUI.AspNetCore.Routing;
using DbLocalizationProvider.AspNetCore;
using DbLocalizationProvider.AspNetCore.ClientsideProvider.Routing;
using DbLocalizationProvider.Core.AspNetSample.Data;
using DbLocalizationProvider.Core.AspNetSample.Resources;
using DbLocalizationProvider.Storage.SqlServer;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Localization;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

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

        public IConfiguration Configuration { get; }

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<ApplicationDbContext>(
                options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

            services
                .AddDefaultIdentity<IdentityUser>()
                .AddRoles<IdentityRole>()
                .AddEntityFrameworkStores<ApplicationDbContext>();

            services
                .AddControllersWithViews()
                .AddMvcLocalization();

            services.AddRazorPages();
            services.AddRouting();

            var supportedCultures = new List<CultureInfo> { new CultureInfo("sv"), new CultureInfo("no"), new CultureInfo("en") };

            services.Configure<RequestLocalizationOptions>(opts =>
            {
                opts.DefaultRequestCulture = new RequestCulture("en");
                opts.SupportedCultures = supportedCultures;
                opts.SupportedUICultures = supportedCultures;
            });

            services.AddDbLocalizationProvider(_ =>
            {
                _.EnableInvariantCultureFallback = true;
                _.ScanAllAssemblies = true;
                _.FallbackCultures.Try(supportedCultures);
                _.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
            });

            services.AddDbLocalizationProviderAdminUI(_ =>
            {
                _.RootUrl = "/localization-admin";
                _.ShowInvariantCulture = true;
                _.ShowHiddenResources = false;
                _.DefaultView = ResourceListView.Tree;
            });
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                app.UseHsts();
            }

            var options = app.ApplicationServices.GetService<IOptions<RequestLocalizationOptions>>();
            app.UseRequestLocalization(options.Value);

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

            app.UseDbLocalizationProvider();
            app.UseDbLocalizationProviderAdminUI();
            app.UseDbLocalizationClientsideProvider();

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

                endpoints.MapDbLocalizationAdminUI();
                endpoints.MapDbLocalizationClientsideProvider();
            });
        }
    }
}