This package requires the FinalIK asset:
https://assetstore.unity.com/packages/tools/animation/final-ik-14290?gclid=Cj0KCQiAmpyRBhC-ARIsABs2EApHCXO_6XW-sbQe-B1sW0SI4sNfS_K2kPIi5HBHBWt-1YYfEwf-SkoaAmIKEALw_wcB&gclsrc=aw.ds