$ sudo apt-get update
$ sudo apt-get install proftpd-basic 

proftpd-basic is installed in your system.

Make ensure the proftpd-basic package were installed using the commands given below,

$ sudo dpkg-query -l | grep proftpd-basic *

You will get with proftpd-basic package name, version, architecture and description in a table

proftpd-basic package basic information: