The default username is admin and there is no password . You will be prompted to set one immediately upon the first login.
After booting, run the command get system status to verify you are indeed running Version 7.2.3 Build 1262. fgtvm64kvmv723fbuild1262fortinetoutkvmqcow2 download link
Since FortiOS 7.2, Fortinet offers a "permanent" evaluation license for VMs. It has restricted features (low encryption, limited interfaces, and no FortiGuard updates), but it does not expire after 15 days like older versions. The default username is admin and there is no password
To understand what you are downloading, the filename breaks down as follows: FortiGate VM64: 64-bit Virtual Machine and no FortiGuard updates)