I managed to compile Backup Server for ARM64 and turn it into a Docker container. This makes it very easy to install it on devices like a Raspberry Pi and many others:
ARM64 Packages: https://github.com/qemus/proxmox-backup-arm64
Docker container: https://github.com/dockur/proxmox-backup
ARM64 Packages: https://github.com/qemus/proxmox-backup-arm64
Docker container: https://github.com/dockur/proxmox-backup