While these tools are widely searched for, they carry significant legal and security risks:

What it does well

On a disconnected VM running Windows 10 Enterprise LTSC 2019? On Office 2016 Pro Plus? Success. It’s lightweight (under 5MB) and doesn't hog resources.

Security researchers have repeatedly found that many Kmsauto downloads include hidden malware: trojans, keyloggers, ransomware, or cryptocurrency miners. The 2016/Portable 1.5.1 version you’re looking for may have been repacked by unknown third parties. Even if an older version was once clean, current downloads from non-official sources are extremely dangerous.