Hello and Welcome!
iTunes is quite famous for taking over functions of CD playback and import. If you want to use Audiobook Builder for importing, the first step is to stop iTunes from automatically importing CDs.
To do this, first go to the iTunes menu at the top of the screen while iTunes is running, and choose preferences. Look towards the bottom of the window for a label 'When you insert a CD:' in the following Popup menu, choose 'Show CD'.
Now when you insert a CD, iTunes will jump to the front of windows to show the CD was inserted. That is as quiet as we can make iTunes
To use Audiobook Builder to import CDs, just click on Audiobook Builder in your dock or click on its window to bring it back up in front of iTunes, and click on the 'Chapters' tab at the bottom of the window of your project. You should see an 'import CD' button in the top bar you can click. Once clicked, it should show your CD and some import options, just click on the 'import' button at the bottom to begin. You can load subsequent CDs in a series after the first, and it should automatically import each one.
Let us know if you run into problems along the way.