Dropbox, Google Drive or iCloud (iOS) are the cloud solutions you can use to sync your notes in Nebo.
When you open Dropbox separately, you can see your synced notebooks as .nebo files. They are the versions you last synced. With Google Drive and iCloud, this functionality is not activated. But rest assured, the latest versions you synced are there, they're just not visible to you in the cloud.
In Nebo, look at the sync icons to know the status of your sync (synced, waiting, syncing, etc.).
To import your notes from your personal cloud to a new device where Nebo is installed, sign in with your MyScript and cloud accounts, and in the side panel, press Sync. Your notes from Dropbox, Google Drive or iCloud will be downloaded and ready to use.