thanks for your reply. I'm not sure about those plugins. As already mentioned, I didn't do anything except for running setup.sh. /etc/ocsinventory-server/plugins was empty after that. When I realized that Apache didn't start, I tried to copy stuff from OCSNG_UNIX_SERVER-2.3.1/Apache there (readable for all), but it didn't help.
I also tried to remove the following lines from z-ocsinventory-server.conf:
# Ocs plugins
But then it's simply failing with the next module:
[Wed Apr 12 13:34:32.781169 2017] [perl:error] [pid 27364] Can't load Perl module Apache::Ocsinventory for server myserver:0, exiting...
So it's not about plugins. It seems that all ocs-provided modules refuse to load.
However, I will thoroughly study the manual that you provided, maybe I happen to discover something.