The Default Library provides fast access to pre-defined categories
Create a new group by tapping the new Group toolbar item
New groups can also have unlimited folders and sub-folders
Groups and folders can be conveniently collapsed by tapping the fold/unfold triangle icon at the right of the group
Re-arrange folders and sub-folders within a Group by dragging them to a new location within the Group
Tap and hold the … icon in a group line and you will be presented actions you can perform on the group including re-ordering groups and exporting the Notes within the group