Unable to create the disk storage.
The Backup Exec service account does not have read and write permissions on the remote computer on which the network share is located. The Backup Exec service account that requires these permissions is on the Backup Exec server that you want to access the network share. You must give read and write permissions to the Backup Exec service account, and then try again.

Guest-mode is disabled on all CIFS shares. Issue is most likely caused after removing the appliance from an ADS domain.
To resolve the issue, enable guest-only access on the appliance as follows:
DELL DR4000 Administrator Guide - ftp://ftp.dell.com/Manuals/Common/powervault-dr4100_Administrator%20Guide_en-us.pdf
DELL DR4000 CLI Reference Guide - ftp://ftp.dell.com/Manuals/Common/powervault-dr4100_Reference%20Guide2_en-us.pdf
DELL DR4000 Manuals and Documents - https://www.dell.com/support/Manuals/us/en/19/Product/dell-dr4000