$ sudo apt-get update
$ sudo apt-get install neutron-plugin-ryu 

neutron-plugin-ryu is installed in your system.

Make ensure the neutron-plugin-ryu package were installed using the commands given below,

$ sudo dpkg-query -l | grep neutron-plugin-ryu *

You will get with neutron-plugin-ryu package name, version, architecture and description in a table

neutron-plugin-ryu package basic information: