$ sudo apt-get update
$ sudo apt-get install assaultcube-data 

assaultcube-data is installed in your system.

Make ensure the assaultcube-data package were installed using the commands given below,

$ sudo dpkg-query -l | grep assaultcube-data *

You will get with assaultcube-data package name, version, architecture and description in a table

assaultcube-data package basic information: