I need to make the design work for labels for cosmetic products. I use Adobe Illustrator CC and Adobe InDesign CC. Is Barcode Maker 3.0 a standalone app or a plug-in software?
No, this is not a plug-in. It's standalone and you can download the installer to deploy it on your PC like a normal application (eg. Adobe Illustrator CC or InDesign CC).
Based on the information found on the official website, you can run the app but it requires purchasing to unlock its full features since it's shareware.