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The mentioned build is unsupported. There is only one exception: The RS1 LTSB2016 version. All other builds of RS1 will not take the updates. You will have to first do a build upgrade (called "feature update" by MS) to a later build (RS5 1809 or 19H1 1903). Note that build upgrades cannot be applied by WOU.

Which Atom CPU?
Do you know, if it is one of those unsupported by 1703 and newer? If you don‘t know, open the device manager and post the exact CPU name here.
I‘m not sure, if CoverTrail supports x64, but it‘ll be better to check the exact CPU name.

@boco
Two/Three exceptions
- LTSB
- CloverTrail-CPU (Windows 10 1607 is supported as long as Windows 8.1 would be)
(- w2k16)

@aker: AFAIK, CloverTrail is 32bit only. That's why I didn't mention it, for 64bit.