The docs at that particular location are for balenaCloud, which is our managed service, rather than openBalena. openBalena is essentially the core components that balenaCloud are built upon, and as you say, because of this there are parts that are not present in it, including multi-user (and the dashboard, MFA, etc. which are all balenaCloud services).
There’s a small section called ‘What’s the difference between openBalena and balenaCloud?’ on the openBalena page that explains this. openBalena itself is based on the core components, the API, VPN, registry, S3 store, database and redis cache. It is intended as a single-tenant, self-hosted system that allows a CLI driven approach to managing device fleets, and is intended for communities that do not require additional features.
Please let me know if there are any questions in particular about openBalena you’d like answering!