Agree with @JonMikelV line of thought (see link at bottom of post for more) but need some clarification.
Maybe @Networld could state the high-level plan here. Is this to start fresh on 2.0.3.3 for some reason?
The “Delete config files” step in the original post seems like a fresh start. It does avoid DB downgrades…
I don’t have a Mac, or know where its updates (e.g. 2.0.4.5) live, but Downgrading How-To seems to think:
MacOS
i./Library/Application Support/Duplicati/updates(service / daemon on High Sierra 10.13.5)
Duplicati on Windows - two version numbers is a long explanation of the different numbers you might see.