Hi Daniel, saw your issue on GitHub. Will check the source to see if there is something special with that folder name
Well, I set up a test site, installed the package, created a content folder with some files, created a datatype to that folder, added a field to a doctype and created a content item. In the field on the item I can select files in the folder.
Will try tomorrow with the field in an Archetype to see how that behaves