Hi,
You have posted in the general Windows UWP forum, since your issue is related to Windows 10 setup I suggest you ask over at the dedicated Windows 10 setup forum over here:
https://learn.microsoft.com/en-us/answers/topics/windows-10-setup.html
You can download the Windows 10 IoT core from here:
https://www.microsoft.com/en-us/software-download/windows10IoTCore
For more information see:
https://learn.microsoft.com/en-us/windows/iot-core/downloads
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(If the reply was helpful please don't forget to accept as answer, thank you)
Best regards,
Leon