Dear Mattia,
although Aolserver is still officially supported, keep in mind that its latest release dates back to 2010, and all new development happens on Naviserver. Also, debian/ubuntu version of OpenACS is still 5.8.1.
Because of this, the project's official and suggested installation method is now by installer scripts here http://www.openacs.org/xowiki/naviserver-openacs
They will give you the latest Naviserver and the latest released OpenACS 5.9.0, requiring very little fiddling.
Hope this helps
Ciao
Antonio
