It is possible to enable both the read-only mode of the Zettelstore and authentication/authorization. Both modes are independent from each other. This gives four use cases:
Not read-only, no authorization
Zettelstore runs on your local computer and you only work with it.
Not read-only, with authorization
Zettelstore is accessed remotely. You need authentication to ensure that only valid users access your Zettelstore.
With read-only, no authorization
Zettelstore present publicly its full content to everybody.
With read-only, with authorization
Nobody is allowed to change the content of the Zettelstore, but only specific zettel should be presented to the public.