It seems that the CloudBerry Backup service account does not have permissions on this windows share. Please check the service account of the CloudBerry Backup Service in the Services list (Start | Control Panel | Administrative Tools | Services). If it is a Local System, you should change the account which has access to that windows share.
You can also change the credentials for network locations directly.
Check out here for more info
You can change account in the Services dialog by right-click the CloudBerry Backup Service, choose Properties. Or you can change it directly from the CloudBerry Backup: right-click on the "Service is started" text label on the left bottom and choose "Change Service Account". The service will be automatically restarted.
Check out our article on how to solve this problem