Using Add-on: SSH & Web Termina

haos_rpi4-64-7.5 is installed on raspberry pi 4 in the Argon one m2 case using balenaEtcher. Using Add-on: SSH & Web Terminal, I enter a script to control the fan. I get an answer (see screenshot). Please tell me how to fix the problem.

There is no “fix”.
The docker container that the addon is is not debian based and does not support apt-get.