If you just want any character's animations then it's actually super simple.
All you need to do is copy a character's anim files (found in their hero folder) and rename every single instance of that class's name to your class's name. For example, I could open the anim folder for the arbalest, copy every single file in that folder, paste them into my class's own anim folder, then open each file one by one, use ctrl+H to quickly search for the word "arbalest" and replace it with customclassx. Then you should copy the arbalest's folder titled "A", that's where the assets are. If any of them have "arbalest" in the name just rename it.

See? Simple.