You are going about it wrong. To install windows you need more than the activation key, you need the install files that you download from Microsoft which are loaded into a usb drive. Then you install windows from the usb drive. Here is how to do it.
Create an up to date USB install media by following the steps outlined here:
https://www.microsoft.com/en-ca/software-download/windows10
Then disconnect or disable all hdd /ssd drives but the one where you will install windows.
Insert the USB media tool, with the windows install files, into the usb port on the computer. Next, startup and go to the board setup and ensure the computer is configured to use UEFI boot settings and SATA mode is set to AHCI.
On the motherboard boot device menu, select the command that identifies both the firmware mode and the device. For example, select UEFI: USB Drive or Windows Boot Manager: USB and list that device in the first boot slot on the board.
Reboot. Install begins.
When choosing an installation type, select Custom. On new disks, the drive will show a single area of unallocated space. If there are partitions, select each one and then "delete".
Select the unallocated space and click Next. Windows detects that the PC was booted into UEFI mode, partitions the drive using the GPT and begins the installation.
NOTE: Any data on the drive will be lost