There‘s no need to „add - map“ these assets within the Forest Pack plug-in on render nodes from the UI. Just please configure on all render nodes corresponding paths to these assets stored in the 3dsmax.ini. The ini file is located by default here:
Also, generally, we recommend resolving all references used by Forest to absolute UNC paths. It's not necessary, but usually, this way you avoid any texture path issues while using distributed rendering.
I hope that helps.