To install the plugin from WP-HR Manager simply got to WPHR Settings → Settings → Addons and select the plugin. Follow the purchase process and the plugin will be installed for you.
If you need to manually install, simply upload the ZIP file from wp-admin → Plugins → Add new → Upload plugin.
You may need to synchronize your license – go to WPHR Settings => Settings => Account. If you are asked for a license number, check the email which was sent to you on completion of your purchase.
If successfully installed you will see a new menu item in the side bar WPHR Settings → Add Fields.