If you do not have a paid license and want to test version 7.4.7, Fortinet offers a for VM64 instances: Requirements: You must have a FortiCloud account.
: Designed for the Kernel-based Virtual Machine hypervisor. v747 : Version 7.4.7. fgtvm64kvmv747mbuild2731fortinetoutkvmqcow2 download link
Download the image from the support portal, boot it in your KVM environment, and log in to FortiCare via the CLI/GUI to activate the trial. Security Warning If you do not have a paid license and want to test version 7