Photos and videos can be seen in Windows Explorer without any problems. Other files cannot. As far as I know, synchronisation (audio, photos, videos, etc.) with Windows works via the iTunes software.
The Digitec community can't really answer that, it's a question for Digitec customer service.
"Questions, answers and discussions should explicitly relate to the products and their function. General questions about your own orders, delivery times or prices should be asked directly to our customer service." https://www.digitec.ch/de/wiki/5340
https://helpcenter.digitec.ch/hc/de/requests/new
You are writing to the community here. To contact Digitec, follow this link:
https://helpcenter.digitec.ch/hc/de/requests/new?ticket_form_id=39231
Hope this helped you