
Please follow the instructions:
viewtopic.php?t=13092

You'll want to download the script
(i.e. Save as...) and then call it with the input folder as first command-line argument followed by amc script options as seen in the PowerShell example:
Shell: Select all
C:\Tools\filebot-watcher.ps1 X:\Input --output X:\Output ...

If you just copy & paste the script file code, then there's no input arguments, no input folder, and the shell will apparently fail to execute with "path is not of legal form" which is overly generic for "cannot watch <empty file path>".