The source code of DUNE-FEM is available as tar-ball (dune-fem-1.3.1.tar.gz). Notice that by downloading the DUNE-FEM software you accept the terms of the licence of DUNE-FEM.
The tutorial DUNE-FEM-HOWTO contains several examples of how to use DUNE-FEM and is also available as tar-ball (dune-fem-howto-1.3.0.tar.gz). You can have a look at the tutorial's pdf document without downloading the dune module here.
The DUNE-FEM software package is free software, licensed under the GNU General Public License (GPL) version 2.0 (or later).
DUNE-FEM needs at least the DUNE core modules
DUNE-COMMON, DUNE-GRID, and DUNE-ISTL at version 2.1 (or later).
For installing DUNE-FEM, please download DUNE-FEM and the DUNE core modules tarballs, and then follow the installation notes. DUNE-FEM will be configured and installed together with the core modules.
Alternatively, advanced users could use this installdune.sh shell script for installing (also downloading) all above mentioned modules into one directory. Change this script to apply your favorite configure flags and so on.