Most antivirus programs (including Windows Defender) flag activators as "HackTool" or "PUP" (Potentially Unwanted Program). You usually have to temporarily disable your antivirus to extract the file.
If you are looking for the password for a file you recently downloaded or want to understand how this utility works, What is the Password for KMSAuto Net? password kmsauto net 149
The genuine KMSAuto Net 1.4.9 is usually around 5MB to 10MB. If your download is 500KB or 50MB, it is likely a virus. it is likely a virus.