Also, if you need help (you have a Cisco support contract or legacy lab), I can guide you there as well.
It’s important to clarify upfront: (e.g., a fake certificate, a forged software license, or academic documentation) for that filename.
Based on the naming convention, Bootable UCSInstall UCOS UNRST 8.6.2.10000-14.sgn.iso appears to be a – likely a recovery or upgrade image.