First off, the mbPlumage asset (I'm assuming you mean this:
https://www.orbolt.com/asset/Haybyte::mb_plumage_system) [
orbolt.com] is not officially supported in Unity so you're kinda at your own risk here.
Furthermore, this particular asset is a heavy simulation asset which doesn't translate very well to Unity as we don't support baking deformations in Unity. I'm curious what you're trying to do with this asset in Unity.
But I'll try to address your two main problems so far with the asset:
So, because the main asset depends on other assets, you need to create a folder inside your Unity project at this exact path: <Root Assets Folder>/OTLs/Scanned and place all the otls for this asset in there - then restart Unity. Everything in the Scanned folder is pre-loaded on startup which ensures all dependent assets are loaded.
The object inputs in the main parameters section are grayed out because they are either counted as asset geometry/transform inputs and promoted to the Inputs section above the parameters - or, they are not supported input types (operator node path parameters that are not filtered on SOP or OBJ type operators only).