CC3 is a character creator tool, not a general import tool. As is stated, it only works with Genesis, Hivewire, and I believe also certain Poser characters, which can be transformed into standard CC3 characters.
For anything else, you need indeed 3DXchange, which allows you the conversion into nonstandard characters for use in iClone. They are
not compatible with Character Creator.
The video would still be relevant to fix any issues with Mixamo characters.