It's just nonsense, your "Buy now" program is incompetent, it reports uBO's chrome-extension:// URL as if it was a network protocol. which it is not. Furthermore it does not details what it supposedly found, and incompetently report whatever it found as "tracker". You should wonder why that program does not report exactly what it finds while you can very easily find for yourself without having to install anything, just open uBO's dev console in your browser and select "Application" pane and look at what uBO stores locally. In the end, what matters is
uBO's privacy policy -- if you do not trust it, don't install it.