Error: The database is unavailable

For what it’s worth, when you install the database from the installation packages, it’s supposed to configure the database for you (it uses configure new single memory). It’s possible for this step to fail, though, in which case you’ll need to run it manually as Oleg said. To run configure new, you’ll need to provide both a redundancy mode (typically single for a local installation) and storage engine (memory or ssd for now).