Customer are using nested folders within a folder that is being displayed by the files widget. The nested folders are listed as ".foldername". Refer to attachment of "Files_Widget.png"
When click on those nested folders(sub-folders) an XML file is displayed instead of the folders contents, refer to attachment of "XML_File.png"
BSS L3 confirm that the Files widget current behavior is expected. The recommendation is to use the Files Explorer widget for any scenario where the user is expected to navigate multiple levels of folder structure. The Files widget is designed more for a list of files instead of navigating around. This is why both widgets are offered.
Then customer test the Files Explorer widget, but it will show all folders in communities but not specific a folder, in addition, it shows folders only , it does not show files (Note: if customer click&open one folder, it will show all its subfolders and files).
It seems that neither ‘Files Widget’ nor ‘Files Explorer Widget' can achieve customer's requirement, customer wants a new feature which can specific a folder, then list both files and subfolders in this folder, and the subfolders can be open in Widget