How to install docker in Raspbian Virtual Machine
The Docker website doesn't know about your operating system and has no docker installation for you. 

Try the one packaged by raspbian:

sudo apt install docker.io


The name is different in some distributions, you can use:

apt-cache search docker


To see if you can find one. If you can't find any, then switch to an older (or newer?) version of Raspbian. 

Or you can search for instructions on how to compile it from source code.