If you're looking for Nora Roberts audiobooks, I pretty much live on Audible. The selection is massive, covers all her series and standalones, and the production quality is consistently good. It's not just about having the books, but the narrators make a huge difference.
I will say, the subscription model can feel steep if you're a casual listener, but for a binge-listen of her backlist, the credit system works out. I used to jump around different free trials, but honestly, finding a specific title in a decent audio format was a pain. With Audible, I know exactly what I'm getting, and the app makes it easy to pick up where I left off. My library's digital service is hit-or-miss for popular authors like her; the holds list for 'The Witness' was months long.
She's written so much that starting with her recent trilogies, like the Chronicles of the One, feels like a solid entry point in audio.