Instructions on using COD Infinite Warfare save file:
2. Download desired COD IW
save file to your desktop and extract it.
3. Select all files within the extracted folder, right click and select Copy
4. Navigate to game save location and paste copied files there.
5. Start your copy of Call Of Duty Infinite Warfare
and your new save status will load automatically.
Game save location
Save folder for Call of Duty Black Ops 3 is different for each game version. Check these out:
C:\Program Files (x86)\Call of Duty Infinite Warfare\players2
C:\Steam\steamapps\common\Call of Duty - Infinite Warfare\players2
For brand new game installation:
If you have a brand new game installation
(which means you didn't play game before using downloaded savegame), it is recommended to start the game, and exit right after the first mission starts.
Do it before following the instructions above. This method will create necessary files within the game save directory.