How to install docker in Raspbian Virtual Machine I first installed docker in raspberry pi using: https://iotbytes.wordpress.com/setting-up-docker-on-raspberry-pi-and-running-hello-world-container/
which successfully did.

I tried doing the same with Raspbian VM but using curl -sSL https://get.docker.com | sh says "Unable to locate package docker -ce"
Please help me with the detailed procedure.
I am using Oracle Virtual Box (Linux 4.9.0-8-amd64 #1 SMP Debian 4.9.110-3+deb9u6 (2018-10-08))
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.