I'd also check that the permissions on the library files are ok. Specifically, the user you're running aolserver as needs to have permissions on the files typically installed at /usr/local/pgsql/lib.
Oh, I see you're using 7.3.2. There are some compatibility issues with 7.3.2 and OpenACS4.6.x. (You didn't say which OpenACS you're using?) You probably want to back up to 7.2.x if this is your first OpenACS install.
You might also want to get AOLserver from http://uptime.openacs.org/aolserver-openacs/ - that's the patched for OpenACS version (see the note at the top about file names being different). I'd suggest sticking pretty closely to those install docs for versions for a first install. Perhaps someone else will comment on whether AOLserver 3.5.6 works out of the box (er... tarball?) or whether patching is required.
(If this is your upteenth million install, please accept my apologies for assuming otherwise. :)
