It sounds like you have a PHP configuration issue. The open_basedir setting in PHP is for security purposes, but it can prevent standard installations of extensions, like JFBConnect, depending on where Joomla is installed. In that case, PHP is preventing the creation of folders that are required to be installed within your Joomla folders and is causing the error.
I'm assuming you didn't really mean 1.5.2 and just left a number off. JFBConnect will not work on Joomla 1.5.14 or below.
To fix, I'd recommend trying the "Install from directory" option in Joomla. You'll need to upload the com_jfbconnect_j1.5_v4.2.5.zip file to your server somewhere and then use that path in the Installer. Hopefully, that will work for you, but if not, let us know.
Thanks,
Alex
Install failure
