My Expat Network use a different username to log in to their website and to use their VPN with OpenVPN. This is why the username you use to log in to the My Expat Network website will not work on your InvizBox.
Click the following link to log in:
You can find your VPN username under the "VPN Username" column, this is the username you will need to use in your InvizBox 2.
The password will be the same as you use to log in to "My Expat Network" website.
You can find out where to enter these VPN credentials on your InvizBox 2 in this article.