When you use an account to set up a SOAP connection to vCenter Server:
you need to assign to these account certain privileges. The easiest way to do so is to create a role in vCenter and assign it to this account. The role will need to get the following permissions, according to backup type you intend to use. This table has been taken from this great Veeam blog note. Check out this article should you want to know how to set up VSS-enabled backups and what else you need for successful Veeam backups.
|Privilege Level||vStorage API Virtual Appliance mode||vStorage API Network mode||vStorage API SAN mode|
|Global||Log event||Log event||Log event|
|Datastore||Low-level file operations||Low-level file operations||Low-level file operations|
|Virtual Machine state||Create SnapshotRemove Snapshot||Create SnapshotRemove Snapshot||Create SnapshotRemove Snapshot|
|Virtual Machine configuration||Disk change trackingChange resourceAdd existing diskRemove disk||Disk change tracking||Disk change trackingDisk lease|
|Virtual Machine provisioning||Allow read-only disk access||Allow read-only disk access||Allow read-only disk access|