Did you install Windows with a stock Microsoft ISO but need to activate against a corporate KMS server?

If so, you just need to install a standard key from here.

To do that, from an elevated command prompt:

slmgr /ipk <licensekey>

Then set your KMS server if needed with:

slmgr /skms <your-kms-server>

Then to actually activate:

slmgr /ato