Thank you for your answer.
No,
I didn't post the full list, because I thought it would be a general problem. Here it is
ls: /media/Data/sys: Permission denied
ls: /media/Data/boot: Permission denied
ls: /media/Data/srv: Permission denied
ls: /media/Data/lost+found: Permission denied
ls: /media/Data/root: Permission denied
ls: /media/Data/mnt: Permission denied
ls: /media/Data/lib: Permission denied
ls: /media/Data/media: Permission denied
ls: /media/Data/tmp: Permission denied
ls: /media/Data/sbin: Permission denied
ls: /media/Data/var: Permission denied
ls: /media/Data/etc: Permission denied
ls: /media/Data/proc: Permission denied
ls: /media/Data/run: Permission denied
ls: /media/Data/bin: Permission denied
ls: /media/Data/opt: Permission denied
ls: /media/Data/dev: Permission denied
ls: /media/Data/usr: Permission denied
ls: /media/Data/home: Permission denied
But when I change it to /home/pi it is working, so I think it's a root problem. I searched for a solution on how to use samba as root. But I could not find a good answer.