12.1.6 MP8 Install failure: "A digitally signed driver is required"

I'm attempting to install MP8 on a Win10 (anniversary update) machine, and I'm getting the following two pop ups:

Sadly, the install will not complete, and keeps asking for a reboot (yellow excalmation on the shield). I checked the install log, and no "Return value 3".

Seems like this a Microsoft issue, so I temporarily disabled the requirement for driver signing...no change.

Did I miss a memo somewhere?

Thanks,

-Mike