Just select a note you want to import and click submit. The selected note will be imported to Confluence as a new page.
Some users are not seeing empty list pages to import after auth process is complete. This happens if you have shared notebooks. We are unable to fix this because OneNote API unfortunately doesn’t return shared pages, see this thread.
As an alternative option, you can ask the notebook owners/creators to import them or copy the notebooks and create as new onenew ones as your personal notebooks and then import them.