$ sudo apt-get update
$ sudo apt-get install proftpd-mod-clamav 

proftpd-mod-clamav is installed in your system.

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

$ sudo dpkg-query -l | grep proftpd-mod-clamav *

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

proftpd-mod-clamav package basic information: