$ sudo apt-get update
$ sudo apt-get install remmina-plugin-vnc 

remmina-plugin-vnc is installed in your system.

Make ensure the remmina-plugin-vnc package were installed using the commands given below,

$ sudo dpkg-query -l | grep remmina-plugin-vnc *

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

remmina-plugin-vnc package basic information: