Duplicati is not a sync tool. Your source files will be split up in separate data blocks and packaged in ZIP or 7Z archives, to enable always-incremental backups, minimize remote storage capacity and other useful features. Read more about it here.
This will result in a single archive (ZIP/7Z) of max 1TB that will be uploaded to the remote location. I guess this is not what you want, restoring a small file will result in downloading one or more very large (1TB) archive files. Read this article for more information.
Did you set the upload volume format to 7Z? This format has a couple of known issues, so avoid 7Z and keep using the default ZIP format until the issues are addressed.
You need all DBLOCK and DLIST files to restore data. DINDEX files speed up local DB (re)creation dramatically. If one or more requred files are lost, you can use the Recoverytool to restore as many as possible from the remote files that you still have.
You need to install Duplicati, or restore files using this Python script without using Duplicati.