sudo apt install cifs-utils

Main Acc

mount -t cifs -o user=<username>,pass=<password> //<username>.your-storagebox.de/backup /mnt/backup --verbose

Sub Acc

mount -t cifs -o user=<username-sub>,pass=<password> //<username-sub>.your-storagebox.de/<username-sub> /mnt/backup --verbose

Main

New-SmbMapping -LocalPath 'Y:' -RemotePath '\\<username>.your-storagebox.de\backup' -UserName <username> -Password <password> -SaveCredentials -Persistent $true

Sub

New-SmbMapping -LocalPath 'Y:' -RemotePath '\\<sub-username>.your-storagebox.de\<sub-username>' -UserName <sub-username> -Password <sub-password> -SaveCredentials -Persistent $true