where is mapping table of Id and it's role stored?

You can use claims-based authorization via policies . After setting windows authentication in your application , you could add custom claim to ClaimsPrincipal ,check user's identity and confirm which permission/role the current user has :

1. You can add a claims transformation service to your application:

   class ClaimsTransformer : IClaimsTransformation
   {
       public Task<ClaimsPrincipal> TransformAsync(ClaimsPrincipal principal)
       {
           var id = ((ClaimsIdentity)principal.Identity);
   
           var ci = new ClaimsIdentity(id.Claims, id.AuthenticationType, id.NameClaimType, id.RoleClaimType);
   
           //read database or flies or query AD to confirm user role by use ci.Name(username)
           if (....)
           {
               ci.AddClaim(new Claim("role", "Admin"));
           }
           else
           {
               ci.AddClaim(new Claim("role", "user"));
   
           }
   
   
           var cp = new ClaimsPrincipal(ci);
   
           return Task.FromResult(cp);
       }
   }
   

2. Add to Startup.cs :

       services.AddAuthentication(IISDefaults.AuthenticationScheme);
       services.AddTransient<IClaimsTransformation, ClaimsTransformer>();
   

3. Set your policy :

       services.AddAuthorization(options =>
       {
           options.AddPolicy("Admin", policy =>
                             policy.RequireClaim("role", "Admin"));
   
           options.AddPolicy("User", policy =>
                           policy.RequireClaim("role", "user"));
       });
   

4. Restrict access to a controller or action by requiring this policy:

       [Authorize(Policy = "Admin")]
       public IActionResult Contact()
       {
          .....
       }
   

You can also use AD groups as roles . Base on your requirement , you can modify above codes to fit your scenario . Manage user/roles could use local database or ASP.NET Core Identity auto-create tables.