SpringSource Application Platform is distributed as a ZIP file. This can be downloaded from here.
To install the SpringSource Application Platform on Unix, unzip the distribution package to the desired installation directory.
For example, to install into /opt:
unzip springsource-ap-1.0.zip -d /opt
This creates a directory called springsource-ap-1.0 under /opt.
SpringSource Application Platform requires write access to the installation directory, in this case /opt/springsource-ap-1.0.
Typically this means it must be run as the user that installed it, or the installation directory's ownership must be changed.