You created Acronis Rescue media on a Mac.
When you attempt to back up the machine with macOS using rescue media, the Backup option is not available. Only recovery can be performed.
The current product design does not support backing up macOS using bootable media.
This applies to all types of bootable media: ISO downloaded from the website, bootable media created under macOS, bootable media created under Windows or Linux.
The ability to back up macOS using bootable media is being considered for implementation in future versions of the product.
Install Agent for Mac on the machine to backup live macOS.