repmgr will create an extension database containing objects for administering repmgr metadata. The user defined in the conninfo setting must be able to access all objects. Additionally, superuser permissions are required to install the repmgr extension. The easiest way to do this is create the repmgr user as a superuser, however if this is not desirable, the repmgr user can be created as a normal user and a superuser specified with --superuser when registering a repmgr node.