I forget where the databases (e.g. Duplicati-server.sqlite and the randomly named per-job databases) land by default for the local system account, but if you don’t see them in the user account that did the install, then see
Installed Windows 10 Fall Creators Update - Now Everything is Missing In Duplicati for another complication of running as a Windows service. Environment variable DUPLICATI_HOME can control where things get stored…
Unfortunately, service is still the harder path, but it does bring benefits. Someday it should get more automatic. There is definitely some learning curve to lots of things, but at least it’s out in the open so that it’s learnable…
Glad to help. When you’ve got enough figured out, you can come back here and help some other person. 