Configure How Users Upload Items
You can decide whether you want users to be able to upload multiple files at one time on a per-enterprise and per-project basis.
You can decide to allow it for your entire enterprise or you can allow it for only some projects, adding more later.
If you decide to allow users the ability to upload multiple files at one time, edit the container's configuration, first for the enterprise and then for the project(s). In the Container Features Configuration window, select Multi File Upload as a container feature.