Although Client Automation r14 supports OSIM deployment of Windows 10 you will receive this error when trying to install from LTSB 1607 media.
"The product key entered does not match any of the Windows images available for installation. Enter a different product key
This error is shown when there is a mismatch between the image name defined in the unattended.inf file and the wim
You can determine the name of the image in a wim by mounting it and then running
dism /Get-WimInfo /WimFile:E:\sources\install.wim /index:1
which will return something similar to
In OSIM we have a parameter WindowsType which is used to select the desired Windows 10 version for installation. In the current templates you cannot select "Windows 10 Enterprise 2016 LTSB" and thus the error is thrown when you deploy the image.
This document advises how to update your existing images or template in order to support LTSB 1607
Client Automation - r14 versions
You can now create new or update existing OS Images with these templates and the additional lines will be included in the WindowsType Parameter