sync store - https://docs.opsmanager.mongodb.com/current/reference/glossary/#term-sync-store

During initial sync of a backed-up deployment, Ops Manager briefly stores slices of the backed-up deployment in a temporary sync store on the Application Database. Ops Manager uses the storage while streaming slices to the Backup Daemon.

Should say:

During initial sync of a backed-up deployment, Ops Manager briefly stores slices of the backed-up deployment in a temporary sync store on the Oplog Store database. Ops Manager uses the storage while streaming slices to the Backup Daemon.