You do not need to hunt for a risky "Language Pack" download. If you own the game on GOG, simply update your client and change your language settings—the system will download the official Brazilian Portuguese files for you safely and legally.
If you prefer not to use the GOG Galaxy client, or if you need to manually add the files, you can do so via the offline installer setup files provided by GOG. You do not need to hunt for a risky "Language Pack" download