The backup of the metadata repository can be undertaken as a separate exercise from the general backup of the data warehouse.
The Backup and Restore process uses PostgreSQL pg_dump and pg_restore respectively. The version of these tools installed with RED is at 12.4. If needed, edit the backup command line from the Options menu in RED to override the path to the executables or add parameters. To backup the metadata database from RED select menu item Backup>Export the Metadata (PostgreSQL pg_dump) and select a destination directory.