You can export from CC3 as FBX, and I notice that one Target Tool Preset option is Blender. There is also Maya, which is close to Mixamo, I believe. There are also game engine options. One of them should be usable with Rokoko; you could check with them.
As CC3 is used to create game characters as well, RL has not problem with you using the characters in other applications. The only thing to be aware of is that if you use bought content such as clothing, you will need an export license for that.