To function as an HIK character and participate in a retargeting pipeline, your character needs a characterized skeleton. To be a target character (receiving retargeted animation) the character also needs a Control Rig.
Your approach to HIK character setup depends on whether you want to use an existing skeleton. The basic workflow to set up an HIK character is as follows.
If you plan to use this character as a target character, you must create a Control Rig. Source characters do not require Control Rigs.