Within the downloads system, you can allow using URLs for download submission, and also link things directly from your file system.
If you edit any of your groups, and select the downloads tab, you will see a series of options which can select on a group by group basis.
If you have a license for the commerce application, you can allow users to charge for files. This is similar to how it is used within the marketplace on our own site. You can see more information on this in the following guide
People without this setting, will only be able to upload single files at a time.
This option will allow for people to use a URL to a file, rather than uploading a file. Note that people can only link to an external URL, if that setting is allowed within the main Downloads settings.
This will allow linking to files which are already uploaded somewhere onto the server, using your servers internal filesystem. Note that you should only ever enable this for trusted groups such as staff groups.
When additional ways of submitting files, such as URL and filesystem, are allowed. The user will see further options above the upload window that can be selected to use these options, as shown in the screenshot below.