Mac OSX kfx output CLI trouble

[troubledMan]

Hi,

I'm on a MacBook running High Sierra, with two accounts (admin, standard user). I have installed both Kindle Previewer 3.43 and Calibre 3.48.0 and the KFX Output plugin (latest version, AFAIK) into the Applications folder of the admin account.
When I convert a mobi, pub, opf file to kfx in Calibre logged to the Standard User account everything is OK. But if I try to do same using CLI, bash spits "command not found". What am I doing wrong?

(Please excuse me if a) this has been questioned&answered before, b) this is not the proper place to ask this question)

TIA