Each course includes a Files Library (2). From the File Library you can upload files directly and use them when creating Units. You can also share files with learners via the Share option next to each file (1).
When a learner traverses a course that has shared files he or she can see a Files option on the course header (3). This option reveals all shared files of the course ready for download.
If you have enabled the Course Summary page, the shared files will also be available in this page for the users to download them (4), even prior starting the course: