need help installing 3.11

[carboniteaddon]

I always login to my Windows computers as administrator, so I don't have those annoying problems. You might want to login using an admin account.

Are you trying to put it in the "c:\program files" folder? That is probably blocked if you are not an admin and your actual WoW folder is probably not in there anymore since a patch about 10 months ago asked to move it.

See if you have a "C:\Users\Public\Games\World of Warcraft" folder.
If so, then the real addons folder would be here:
"C:\Users\Public\Games\World of Warcraft\Interface\AddOns"