You are downloading Gammu binaries for Windows. The files are available as installer (.exe) or just an archive (.zip). The -Minimal variant has slighly less features compiled in and contains Gammu.dll, which you might use in external programs. There are also python-gammu binaries, which include all needed parts to use python-gammu in your python programs, just choose the version matching Python version you use.
Released on May 29, 2013, see detailed information.
You can not find your platform here? Choose the correct one on complete listing.
Should you be interested in git access or git snapshots, you can find them on development page.