Ok, I just realized the drive you’re trying to flash to is the system partition. Your entire operating system is on the disk, and the process that is running etcher is controlled by that OS.
So, what exactly are you trying to do? convert the Windows computer you are using to HiveOS?
If so, you should realize, that’s going to erase that entire disk, so you won’t be able to use that computer, except for mining.
But if that’s what you want to do, it looks like the website’s instructions are saying to download the image flasher image, and flash that to a USB thumb drive using Etcher. You download it from here: http://download.hiveos.farm/
Then, you’ll put that flash drive into the computer you want to use to mine, which could be the very same computer you used to flash the image with, and boot from that image. This is a more complicated process, outside of the scope of this support forum, but it looks like they have a forum that can help you if you get stuck: Booting problems - OS setup and Linux - Hive OS Forum