After configuring central backup feature on newly installed SolusVM, central backups do not work.
Central Backups feature has been deprecated.
For new environments, the recommended backup solution is Automated backups: Automated Backups
Vote for a feature request regarding implementation of different backups in solus.io: https://solus.uservoice.com/forums/914134-help-us-improve-solus/suggestions/34925440-proper-vm-backups
Note: central backup feature works for already existing SolusVM environments. However it is not available to install for the newly deployed SolusVM product.