The note taking app Joplin should be able to sync files between a phone and a desktop. However, I have not managed to get this to work.
I authorized the same dropbox account on both the desktop and the phone. However, when I sync on the phone the notes that are there on the desktop do not appear.
Below Synchronize it says (on both devices):
Completed: [recent date]
Last error: Error: POST files/list_folder: Error (409): {"error_summary": "path/not_found/..." , ...}
Joplin: https://play.google.com/store/apps/details?id=net.cozic.joplin