Hairibar.Ragdoll is a Unity package for making ragdolls and animating them with keyframed animations.
The How to Install section explains how to set it up. Using it with Animancer is no different from using it with Animator Controllers.
The StateMachineBehaviour scripts it uses for Mecanim Integration are not relevant to Animancer's Finite State Machine system since your states can just set those values directly.