By default, SNAP packages are
not allowed to access
/media, or any other
/ root folder. The SNAP sandbox will deny access unless you have explicitly granted access to
removable-media.
Grant access to
removable-media if you want to process files in the
/media folder with FileBot:
Shell: Select all
sudo snap connect filebot:removable-media

If you want to give a SNAP package full access to your local system
(e.g. /mnt) then you can use
--devmode when installing the application to
disable confinement entirely.