You'll have to check with Filebot and see what environment it is assuming. Remember that Hazel does not run in the same environment as the commandline so you'll likely have to set certain environment variables yourself. Also, search the forums as there might have been others that have figured this out with Filebot.

the embedded script is a cut and paste of my script for movies that works when run within terminal. the only thing I can figure else to try is replace
"Volumes/M0vies/Download/Plexed/" with "$1" to call the file that triggered the Hazel rule (rule being conditions within a watch folder based on file/folder)
or what the environment Filebot is expecting to run in?
so far the script seems to partially work as it refreshes Plex, but I get an error on the file itself that it tries to rename.