This index can be created with a single click by Workspace Owners or Administrators.
Navigate to the relevant workspace and click 'Options' and then 'Settings'.
Under the files section, locate 'Export file index' and click 'Download'.
The image above shows you a selection of a file and folder index. The pdf file that's downloaded will display your file and folder structure as it appears in your workspace.
If you would prefer an editable Microsoft Word version of the index, convert the pdf file using this free online facility.