The Wire import it part of the roadmap of Twinmotion, and should be available in TM 2025.1 final
https://portal.productboard.com/epicgames/3-twinmotion-public-roadmap/tabs/5-in-progress
concerning the fbx, it should be supported, whatever software is used.
If you try to import the fbx in a viewer, (like the Autodesk FBX Viewer) do you see the model?
Have you tried with a smaller object, for testing??