The virtual server backup functionality is designed to store an image of a virtual machine (VM) on a safe store that remains available, even if there are problems on the node where your VM is located. At any time when you need it, you can restore this image and get the VM as of the day of the backup.
VPS backup is for internal purposes from the client side only. The ability to download images is missing.
It is possible to create a task for reserving a VM on a schedule.