Hello,
the slapd-meta backend (OpenLDAP version: 2.4.26 and 2.4.28) has an own rewriting module. If I want to use rewriting and remaping, do I have to install rwm-overlay although I have meta installed?
not sure what you mean by "installed"; if you mean "loaded" when built as run-time loadable modules, then the answer is "no". The two modules (back-meta and slapo-rwm) are orthogonal.
p.