Update:It does not happens on all WS2016 machines, it happens only on computer where Secure Boot is enabled. This also means that this will happen on every machine that is using Secure Boot, regardless of OS version. It is a confirmed bug.
Yesterday Microsoft released Windows 10 1703 and also ADK 1703. But it fails to install correctly, the ADK actually installs, but it is the WIM mount driver that fails, du to this absurd message.
A digitally signed driver is required
The message indicates that the driver Windows Overlay Filter is not signed.
According to this https://social.msdn.microsoft.com/Forums/en-US/1fa43cc7-a82d-4dd3-8d28-f76fe2d7593e/hardware-development-kits-for-windows-10-version-1703-april-2017?forum=wdk , the solution is to disable Secure Boot, really???