You can use them normally as I do also with Maxtree ecc..
Regardging FP plugin it works perfectly, even the Forest color map
from Standard materials.
Just enable the "Legacy 3ds max support"
Regarding any plant libary (HQ plants, maxtree ecc) just
convert the vray version models of them into arnold with
arnold scene converter made by Mads and then use them
as custom objects when you generate FP objects.
Regarding the ready to use Forest Pack libraries, there
you have to create your own libraries because these
galleries are made for vray/corona.
Unfortunately arnold wich is for me the best renderer
for many reasons (I am rendering over 30years 🙂 🙂 )
and has the best devs, is not so famous as vray and corona.
This is the beautiful star system we live in 2020...
And if you are using Forest Pack libraries, they have a preset for Arnold Materials as well.
Thanks for your answers, i will watch this. I will definitely need you again.