Issue with docker while installing the tools from websploit.org

[logicito]

Apologies if this is the wrong place to ask the question, I am installing in Kali the tools from the websploit.org site (as part of an O'Reilly course), at the end of the installation I get an error with docker: "/usr/local/bin/containers: line 36: docker: command not found, if I try to start the service it says "unit: docker.service not found". Please could you guide me to the right place to get help, thank you