I was able to import the website (backedup into .DAF-archive) into Local WP in the follwoing way (thanks to an other topic):
- extract the archive made with Duplicator (.DAF archive) with DupArchive Extractor,
- place wp-content folder in a new folder e.g. named ZIP
- place -sql file (database backup) in the same folder
- make a ZIP-archive of the content of this forlder
- use this ZIP-archive to import website into Local WP.