Holdkey is available for all Windows versions.
If you install version 3.1 you will probably see the Microsoft Defender Smartscreen. See images below.
You need to click 'more info' and 'run anyway' to install version 3.1
After clicking more info you will see Channels B.V as verified publisher.
It is absolutely safe but it takes some time by Microsoft to remove this warning.
Version 3.0 already passed this issue and does not give this warning.
So if you prefer you can download version 3.0 HERE but 3.1 is better.
Holdkey free version 3.1