Version 6.21 is an older version of the software. Current versions have moved toward PC-Check UEFI for modern hardware.
The .iso file is a disk image that allows technicians to burn the software to a bootable CD/DVD or, more commonly today, create a bootable USB drive using tools like Rufus. eurosoft pc check 621 iso upd
Are you deploying this utility in a or modern UEFI environment? Version 6