Hello! The armature/skeleton that gets exported using the FBX option for Blender (same with the Unity option) can't really be used for animations inside Blender as it seems impossible to use Inverse Kinematics (I've tried for 2 days). Apparently it's related to how the bones are connected in the extremities.
Any solutions?

Thank you!

Thank you so much! You saved me tons of time. Just seeing that it was possible made me remember that I actually didn't know how to set up the IK correctly inside Blender.

Glad it helped.

Hey there! I tried this strategy because of the same problem, the bones weren't connected when imported to Blender. However I've got some questions.

Should I do this step with every bone or how can I know in which bones to apply the constraints. Does the chain length varies depending on which bone you apply the constraint?

I planned on saving some bucks by not buying iClone and animating in Blender instead. However importing this model into Blender without the bones connected really made me mad and on the verge of returning CC3.
If there's something else I should know, please tell me. And thanks a lot for helping!

If you wish to animate in Blender, then you need to know Blender animation and rigging in and out.
But if you are saying bones are not *connected* in Blender, it just shows otherwise. Sorry.
Bones are always connected and the connection can be verified in Edit or Pose mode by black dotted lines connecting bones (as well as at the individual bone properties panel)

Blender does not give you anything for granted like iClone and CC. You actually have to make a lot of things happen yourself.
IK is one of those things. Yes, you have to built IK chain yourself.
I have just shown basics to OP, who was struggling to find the way to do it. The rest is up to you.

I am not a Blender Pro and I set IK occasionally, when I need to quickly test weights for some cloth I made.
You, on the other hand, who wish to animate in Blender have to do some research and study on this matter using Blender resources and communities.
I am sure there is a way to automate IK and make IK/FK switchers in Blender.

We - the iClone users do not have to care about it much because it is granted.

Good luck.

Unfortunately, the current version of CC3 doesn't work with the current version of Blender.  Hopefully, Reallusion will fix it soon, because  it really is awful, and Blender is getting used more and more.  Both Standard and Game Base are broken.  The bones are not properly connected in a chain, and twist bones are superimposed over or under other bones (but don't move with them).  You have to manually re-weight-paint the bones, connect them yourself, and delete the twist bones.  In other words, you have to rig the character yourself.  And that is just Standard export.  The Game Base has the same problems, plus complete misalignment of bones.  I do hope this gets fixed soon, as I also bought CC3 and countless other associated packages for hundreds of dollars, and can't use the product.