You do not need this pack if:

The US Pack (Complete)

• Includes: Uncut Zombies mode, violent finishers, explicit language (swearing in the campaign).
• File Size: ~5.2 GB.

Verification: If the game still won't launch in English, right-click the game again, select Installed Files, and click Verify integrity of game files to ensure all assets were downloaded correctly. Manual Fix for Region-Locked PC Versions

Warning on File Size: The full English pack (including high-resolution audio for Zombies) is approximately 12GB to 18GB. Ensure you have hard drive space.

If your copy of Call of Duty: Black Ops 3 is locked in a different language (often Russian or Japanese depending on your region), you may need an English language pack or a manual file modification to switch it. PC (Steam) Installation & Language Switching

Alternative Method (Steam users only):