Since Chrome apps are now being deprecated. Download postman from https://dl.pstmn.io/download/latest/linux

Go to Download folder -> "right click" -> "Open in Terminal"

Installing Postman (Verify your version of file in below command)

tar -xzf Postman-linux-x64-7.13.0.tar.gz

If any version is installed before, remove it.

sudo rm -rf /opt/Postman

Move Postman

sudo mv Postman /opt/Postman

Create a desktop file

cat > postman.desktop <<EOL
[Desktop Entry]
Encoding=UTF-8
Name=Postman
Comment=Version Control Tool
Exec=/opt/Postman/Postman
Terminal=false
Type=Application
# Before v6.1.2
# Icon=/opt/Postman/resources/app/assets/icon.png
Icon=/opt/Postman/app/resources/app/assets/icon.png
MimeType=application/vnd.mysql-workbench-model;
Categories=GTK;Database;Development;
EOL

Move Desktop file:

sudo mv postman.desktop /usr/share/applications/

Remove the tar:

rm Postman-linux-x64-7.13.0.tar.gz

You're Done !