Thanks for the reply Squid,
I made the DNS and IP static and the issue persists.
I am most definitely connected to the network as I can ping websites from the machine.
Do we know their activation server address?
UPDATE: I deleted the key file manually from the USB - rebooted and went through the registration process again - issue still persists
RESOLVED: Rebuilt USB stick with a clean version - discovered that my issue was probably being caused by an incorrect time/date in unraid settings. Sorry for the post and thanks for the help!