$ sudo apt-get update
$ sudo apt-get install libfreeradius2 

libfreeradius2 is installed in your system.

Make ensure the libfreeradius2 package were installed using the commands given below,

$ sudo dpkg-query -l | grep libfreeradius2 *

You will get with libfreeradius2 package name, version, architecture and description in a table

libfreeradius2 package basic information: