First, you posted in the Backdoor section, instead of the support section.
Also, as clearly explained in the manual and your purchase receipt as well, you should always use the support email for questions about orders and activations because, now my next question would be some details about your order which can't obviously share in public. Always use the support email and not the forum, for any question related to activation.
To make it easier for you, a general reply might be the activation will not normally ask for a Computer ID, only the offline method would be, if it cannot access the internet, and if you really need to do an Offline activation, the KIAH manual explains that as well.
If you are connected to the internet, but still the Offline activation comes out, the most likely cause is either your antivirus or firewall is blocking access to the activation server, so the program thinks there's no internet, so you need to fix that, by disabling the Firewall and/or configuring the antivirus to exclude the WHOLE "Addon Manager" folder.
