Select or "Extract to..." using a tool like 7-Zip or WinRAR .

FitGirl repacks usually include a tool called Verify BIN files before installation.bat . Once you have extracted the files: Run that batch file.

The software will automatically pull data from Part 2, Part 3, and so on to recreate the full installer.

You do not need to extract Part 3 individually. Right-click on Part 1 (the first file in the sequence).

It sounds like you’re trying to handle a multi-part archive for . When dealing with files labeled as ".part1," ".part2," etc., you are looking at a split compressed archive. Essential Guide for Multi-Part Archives