hi Bueymo, and welcome to Tikiwiki community!
Try profile Category transtitions as a proff of concept to produce a document workflow system.
And Tiki5 seems to allow using webdav access to files in file galleries (not to forum item attachments)
However, much of the power of tiki as document management comes from using documents in Wiki pages (with or without Wysiwyg Editor ), which allows a much faster way of collaboration on documents.
For longer documents you can use Structures (like Wiki Books) (see its documentation)
Welcome on board!