The default username is admin . There is no password set by default, but you will be prompted to create one upon your first login.
While the keyword specifies .kvm.qcow2 , you may want to run this image on Proxmox (uses QCOW2 natively) or VMware. For VMware ESXi: The default username is admin
FGT_VM64_KVM-v7.2.3.F-build1262-FORTINET.out.kvm.qcow2 virtual disk image for the FortiGate VM64 firewall running on the KVM hypervisor The default username is admin