Each artwork is linked to an artist on your account. That is why the app asks for at least one artist before you can create a catalog.
In the private area open “My Artists” and use the button to create a new one. A clear display name is enough (yourself, a studio name, or a pseudonym).
You can add more artists later if you manage several lines of work or a shared archive.
Wireframe: artist list and action to create a new artist.