The Windows 11 requirement has been widely known and made available since the middle of the Summer of 2025. It's also in the system requirements.
You only needed to scroll down the page - https://turbotax.intuit.com/personal-taxes/compare/desktop/
Product download, installation and activation requires an Intuit Account and internet connection. Product limited to one account per license code. Operating systems required: Windows 11 (64-bit), macOS Sonoma 14 or later. Software will not install on Windows 10, macOS 13 or earlier operating systems. Please confirm your operating system prior to purchase. See full system requirements
no one is being ripped off, if you missed the system requirements and bought the wrong s/w, you can request a refund here