I used their online chat support rather than calling up. This page should put you in the right direction:
https://www.groovypost.com/howto/activate-windows-10-license-microsoft-support/
Congrats on the successful install. Enjoy
Cheers pal, I'll get round to it tomorrow and i was right. PC2 runs almost perfect with the RX580 so the vega will breeze it stock.