Direction needed

I own a few custom 3D models and I want to use them in my project. Unfortunately, the person I depended on do get this done is unavailable. This leaves me either looking for someone with this skill or seeking to learn this skill myself. I have 3D models in t-pose which I have imported into the project and look perfect. I literally have hundreds of animation sequences purchased in preparation for this point. What I need to know is, step by step, is how do attach the models to to the animations?

I have googled and I’m getting a wide range of answers. I need some explanation that is entirely UE centered and will properly achieve what I need to.

Thanks in advance.