Error detecting Kindle HDX 7 to Calibre on my Mac

Hello, I'm hoping someone might be able to provide some assistance.

I have a Kindle HDX 7 connected via USB to my Mac, which is running Calibre. I can select books and even click "Send to Device" but the books don't transfer and it always results in an error.

Any idea what the problem is and how to fix it so I can send books to my Kindle?

If I can't get Calibre to connect and transfer books should I look into using Calibre Companion? If I use CC would the books show up in the Kindle under the native program?

Thank you and I appreciate and help.