$ sudo apt-get update
$ sudo apt-get install fusionforge-plugin-authcas 

fusionforge-plugin-authcas is installed in your system.

Make ensure the fusionforge-plugin-authcas package were installed using the commands given below,

$ sudo dpkg-query -l | grep fusionforge-plugin-authcas *

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

fusionforge-plugin-authcas package basic information: