What exactly do you mean with "local storage system"?
You can generally download files from the PBS Webinterface via the file explorer (under your datastore > Content) by clicking the small folder icon when you expand the backup group. This only works for file-based backups done with the proxmox-backup-client
or container backups.
If you want to restore the files from a VM you can do so through the Proxmox VE WebUI by selecting your pbs-storage > VM-backups and then File Restore.