OK.
There is the main problem, that I'm not able to configure WebAdaptor. I've tried OpenLDAP, Apache DS, Apache Tomcat and IIS. With no results.
I just cannot find any info about how to configure WebAdaptor to use Authentication from LDAP. The only help is about using Windows Authentication that uses Windows AD. I tried that too, and with success, but there were licensing problems, so that was no for me.
All that authentication I need for OGC services only.