While you are creating your installation media USB stick, using Intel Windows 7 USB 3.0 Creator tool, all needed USB 3.0 drivers are included. If it doesn't work for you, you can try the following:
--You can use the procedure from the following link:Installing Windows 7 on the NUC5CPYH or NUC5PPYH (Braswell NUC) – Also valid for Skylake NUC! – The NUC Blog
--You can follow the steps for Windows® 7 installation on the Intel® NUC6i7KYK: NUC6i7KYK & Windows 7
Hope this help
This message was posted on behalf of Intel Corporation
Thank you lw1948 for your collaboration.
markm1259, you can try Leon's suggestions but it is important to remember that the operating system you are trying to install is not supported by the product you have.
You can confirm the information by clicking on the following link:
Supported Operating Systems for Intel® NUC Products
Basically, this means that even if you are able to install Windows 7*, the functionality of the unit will be limited to the generic Windows drivers and the Windows compatibility tool; eventually, you will face compatibility issues as we don't have drivers for Windows 7* for the Intel® NUC Kit NUC6CAYH.
Hope this information helps.