GPG key installation issue on Ubuntu 18.04

I was trying to install an application on the Ubuntu18.04 machine and was trying to get GPG Key installed as a pre-requisite.

Btw GPG is the Gnu Privacy Guard and it is an implementation of OpenPGP (Open Pretty Good Privacy). It is an encryption technique that is used in a number of different applications such as code signing for Linux code repositories and source code repositories like GitHub.

— — Issue

I was using the following command provided by the application installation guide.