Even if you got it to work I wouldn’t recommend using it.
I’ve tried this package and it’s basically a glorified video player. It renders the animation directly onto a render texture which makes it heavy on performance as it’s not a cheap operation. If you’ll rely on it as a base for your game you’re going to see a massive drops in performance as you add more and more simultaneous animations.
Basically this package has been created so they can show that they have a Unity integration even if in reality they don’t.
If you want to use the exported Sprite Sheet, you basically need to create your own importer for this that creates a native Unity animations from the exported data. But be warned that not all of the animation parameters that are exported in Sprite Sheet xml’s can be natively transferred to Unity. E.g. Unity doesn’t allow you to skew sprites natively. So you’ll need to create a sprites in Harmony for your skews.
The other way is to use the EaselJS format and have all of your sprites “pre-rendered” so you can simply swap sprites in your Sprite Renderer component. You’ll also get a xml so you can create an importer for it that creates the animations automatically. As this will only require swapping sprites at correct frames it’s much easier to create.