[Part 2] Download torrent & newsserver package(s)

[Fred]

Maybe it helps if you change permissions for the parent folder /mnt/nas. For me the owner is xbian:xbian and the permissions are set to 755. You could also try making an extra folder if you don't want to change the settings for /mnt/nas (because this might interfere with other things you do with this nas) with these permissions and put the download folders in here (so /mnt/nas/newfolder/downloads etc.).
Seems that nzbget tries to create these folders in /mnt/nas so the permissions/ownership should be set right for this folder too.