FTD is the unified firewall image running on the firewall itself. To manage FTD there is an option for Onboard management called Firepower Device Manager (FDM) which is only available for low to midend appliances (<= ASA 5545-X)... so not suitable for your FP4100 firewall. FDM is limited in functionality, thats why its only for smaller deployments that only need a subset of features.
To manage your FP4100 running FTD you will need Firepower Management Center (FMC) which you can install using a virtual machine (KVM/VMware) or a dedicated physical appliance.
