Quote:
"If you are prompted to enter a product key, click Do this later and give it a few days, Windows 10 will activate automatically.
Activation servers might be overwhelmed at the times because of the volume of upgrades, so give it some time if you get an error message such as (0XC004E003, ,0x8007000D, 0x8007232b or 0x8007007B) Windows 10 will eventually activate as long as you upgrade using the appropriate method"
Source:
http://www.groovypost.com/howto/fix-windows-10-product-key-activation/
So perhaps patience and persistence might be required here?