There's another thread on here (search for it in the search bar) that i've replied to that details how to do it. I'll confirm how it works tomorrow and make a tutorial hopefully.

Check other threads on this forum (use the search bar) to find others discussing this, it's been answered in that thread.

Try running plutonium.exe as an administrator.

If that doesn't work - add %localappdata%/plutonium as a folder exclusion in Windows defender. Maybe defender is blocking the download.

Can you screenshot your MW3 folder please?

emilartzz Have you ran exclusions.bat from the instructions page?