$PWD is the current working directory. That's where the *.psm license file is expected. That is mapped as /volume1 inside the container, and then accessed accordingly.
I've installed the docker package and works so far but when I try to install the license I get the following error: sudo docker run --rm -it -v $PWD:/volume1 -v data:/data rednoah/filebot --license /tmp/FileBot_License.psm Error during startup net.filebot.cli.CmdlineException: Invalid License File ...