hi, martin i from argentina i dont talk english very good.for add material you have Decompress the downloaded archive.
For installation, launch Artlantis, display the catalog of Medias (Menu Window > Catalog). In the toolbar of the Catalog window, click on the concerned icon (Shaders, Objects, Images), then drag&drop the new folder into the Catalog manager (Left column). The new Medias are displayed at once in the right part of the window. tienes que arrastrar con la ventana abierta del archivo descomprimido hasta el que agrgaste.