I hope you don’t mind that I moved your support request to a new topic from a feature request discussion.
Is this something that has changed with a currently running backup, or are you trying to get set up initially?
Duplicati’s default install only runs when a user is logged in. It starts then, and it runs as that specific user.
This might not result in what you’d want, especially if the server has multiple users and you’re their admin.
Migrating from User to Service install on Windows explains how to make a Windows service to run at boot.
Install Duplicati as a service is a video on how to do this. It’s somewhat old but should still be roughly right.
Personally, I suggest using the –server-datafolder option when you run Duplicati.WindowsService.exe, or Windows version updates are going to wipe the SYSTEM profile, so Duplicati DBs move to Windows.old.
Using --portable-mode is another way to avoid having your service get clobbered by Microsoft by updates.