$ sudo apt-get update
$ sudo apt-get install account-plugin-mxit 

account-plugin-mxit is installed in your system.

Make ensure the account-plugin-mxit package were installed using the commands given below,

$ sudo dpkg-query -l | grep account-plugin-mxit *

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

account-plugin-mxit package basic information: