Right-click on Part 1 and select "Extract Here" using WinRAR or 7-Zip . It will automatically pull data from all other parts, including Part 7.
If prompted for a password, it is typically www.apunkagames.net or apunkagames . Run Setup: Open the extracted folder and run Setup.exe . download-devil-may-cry-apun-kagames-part7-rar
Make sure you have downloaded every single .rar file (Part 1, Part 2, ..., Part 7, etc.). Right-click on Part 1 and select "Extract Here"