Sometimes you have to close Feral Heart and restart it after downloading a new mesh or else when you try to load it it shows up white so try restarting first.
I'm not much of a map maker but if the first suggestion doesn't work and since you say the mesh came with a material file open its mat file and get the mat from there. After that type it into the object maker manually but make sure you're typing it in exactly the way it's written in the mat file.
Goodluck
