Hi sevenofone,
The author of the scripts has labeled them with: Works with Release: 13 and greater.
Of course, things might change, a test with the current R19 didn’t seem to show any problems.
The IK question is not related to the tutorial, Please don’t mix questions here, as that will become hard to sort. Thanks for considering.
It is a longer discussion, of how you want to use it, in which combination etc, so nothing for a mixed thread, but here is a short intro with some tutorials about it. Yes, no Maximio, as this is just a Library added to one’s rig, nothing more, Keyframes to name it.
Off-Topic:
To add IK is based on the Object Manager> Tags> Character> IK Tag. The Tag need to sit where the IK chain starts, and the Tag (while active) will guide you through the process to define which Joint ends the chain and it will with a press of a button create a Goal and a Pole.
IK tutorials
https://www.cineversity.com/vidplaylist/ik_fk_arm/ikfk_arm_part_1a
This series is designed to dive deep into the idea of IK/FK
https://www.cineversity.com/vidplaytut/ik_tag_part_i
(sorry about the audio) See also part 2 and 3
https://www.cineversity.com/vidplaytut/nab_2018_rewind_dan_pierse_c4d_in_a_broadcast_sci-fi_and_thriller
@ 16:08
https://www.cineversity.com/vidplaytut/nab_2018_rewind_ej_hassenfratz_painless_character_rigging_using_deformers
@15:17
https://www.cineversity.com/vidplaytut/rigging_a_surgical_robot_setup_inverse_kinematics_for_robotic_arm
All in all, The main idea for an FK animated object to use IK, is based on the use of the settings IK/FK, Reset FK, as well as , Advanced: Update IK on FK
https://help.maxon.net/us/#TCAIK-ID_CA_IK_TAG_SOLVER_GROUP
All the best