Greetings!
For the fur texture, place the fur textures you wish to use in FeralHeart>media>textures>masks.
As for the animations, I've seen you've already posted a thread regarding this.
As Xspirit explained, old custom animations need an update to work with 1.17 since a new animation named "TailScale" got added.
To convert the animations so that they work in the new update, check out
this thread.Hope this solves the issues you're having.~