I am trialing your product, and the OneNote sync does not appear to be working. It's not showing me the notebooks from OneNote, nor is it uploading my test Outline notebooks to the cloud.
I've looked directly through onenote online as well as the mac desktop client, and can state that your app is not pushing changes up, nor is it recognizing existing notebooks.
I've tried logging out and back into onenote from your sync preferences pane, and restarting my system. Nothing seems to help.