Hi @Nit, welcome to the forum, and welcome to KPN :)
The message indicates that you are not connected to your home internet. So, make sure you are using a device that is connected to your own wifi. Or, that you are using a cable that is connected to your own modem.
If that is the case, it is possible that your connection has not been fully delivered yet. Sometimes administrative things can take an extra couple days. During that time, the internet works, but our system thinks it isn't fully ready yet.
So, if you still can't activate Netflix, the quickest way to get this checked is calling us (0800-0402, free). Or, if you're not in a hurry, fill in your forum profile and reply here when you've done so. Then I can take a look to see what is going on.