That is it, I waited for an about one hour but it didn’t stop. I had to destroy the job via rails and tried to configure LDAP Sync again and again with another settings but it didn’t work no matter what I did.
It’s very sad, I would like to implement Zammad at my workplace, but there are so many problems.
I’ve installed Zammad one more time, this time via package. The migrate from OTRS was faster. And then I was able to integrate LDAP. I’ve used another DC-server, Windows 2016 and ist has worked without any problems.
I don’t know it was because of installation via package or of another server OS but the idea for another DC-server was very good. Thank you @TomGem !