Folders can only be created in the profile group's internal media library.
Content > Media Library
Click on Create folder
Enter a name for the new folder
Click on Create folder
Add files to the folder:
a. Upload new files: Open the folder and click on Upload new file click
b. Move existing files to folder:
1. Select one or more files from the media library
2. click on Move click
3. select the target folder you want
4. Move file click
Content > Media Library
Select and open an existing folder
Click Create folder
Enter the name of the new subfolder
Click Create folder