I don't believe HIDs have the ability to install arbitrary drivers. Windows will try to identify the device and locate the driver via Windows Update, or use a generic HID driver. Or the OEM may have preinstalled drivers.
In any case, a malicious keyboard can simulate keypresses and pwn your machine that way. No evil driver needed.
In any case, a malicious keyboard can simulate keypresses and pwn your machine that way. No evil driver needed.