Thanks for joining the thread, @wz777.

Windows 10 in S mode runs only apps from the Microsoft Store to increase security and performance.

Since QuickBooks Desktop Pro 2021 isn't available in the Microsoft Store, you'll need to switch out of S mode. This way, you're able to install the product.

There's no charge to switch out of S mode, but you won't be able to turn it back on.

You can check out this link to download our product: https://downloads.quickbooks.com/app/qbdt/products.

After downloading, follow the steps in this article to install it: How to install QuickBooks Desktop.

Let me know if have any further questions or concerns. I'll be here to answer them for you. Have a great weekend.