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

gadmin-proftpd is installed in your system.

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

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

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

gadmin-proftpd package basic information: