The barcode scanner feature requires a Dynamsoft license. Refer to the link for the pricing details.  

After the required license has been purchased, there is a key “BarcodeScannerLicenseKey” in the API web config file for the Dynamsoft barcode scanner license key. This key needs to be updated with the new license key.

Once the setup is done, Barcode can be enabled/disabled on the web-store through an "Enable Barcode Scanner" setting available under the Manage Store screen in the admin application.