NVIDIA EP (NvTensorRtRtxExecutionProvider) not auto-downloaded on clean system

[Sthen111]

Issue: NVIDIA NPU EP Download Error
Env：
NVIDIA GeForce RTX 3060 Laptop GPU, driver version 32.0.15.7324, cuda version 12.5
windows 11 Pro, 24H2
windows Update to KB5065789(2025-09 D)

To test whether CppConsoleDesktop can automatically call the NVIDIA execution provider on a clean PC, I ran the original sample (with only minor debug prints added)：

std::cout << "Getting available providers..." << std::endl;
auto catalog = winrt::Microsoft::Windows::AI::MachineLearning::ExecutionProviderCatalog::GetDefault();
auto providers = catalog.FindAllProviders();
for (const auto& provider : providers)
{
    std::wcout << L"Provider: " << provider.Name().c_str() << std::endl;
    try
    {
        auto readyState = provider.ReadyState();
        std::wcout << L"  Ready state: " << static_cast<int>(readyState) << std::endl;

        // Only call EnsureReadyAsync if we allow downloads or if the provider is already ready
        if (allowDownload || readyState != winrt::Microsoft::Windows::AI::MachineLearning::ExecutionProviderReadyState::NotPresent)
        {
            std::wcout << L"  Ensuring ready..." << std::endl;
            provider.EnsureReadyAsync().get();
        }

        if (!provider.TryRegister())
        {
            std::wcout << L" Failed to register provider!" << std::endl;
        }
        else
        {
            std::wcout << L" Successfully registered." << std::endl;
        }
    }
    catch (...)
    {
        // Continue if provider fails to initialize
    }
}

The app detects NvTensorRtRtxExecutionProvider in the catalog, but TryRegister() fails, and the EP is never actually downloaded or becomes usable.

Getting available providers...
Provider: NvTensorRTRTXExecutionProvider
  Ready state: 2
  Ensuring ready...
 Failed to register provider!
ONNX Runtime Version: 1.23.2

According to the official documentation, NvTensorRtRtxExecutionProvider was released in version 1.8.14.0 via Windows Update in "2025 9D."
However, why am I not getting the execution provider (EP) properly, even though I'm using the corresponding system version?