Downloaded MoP from the site, but can't run it.

So yesterday I downloaded MoP from the Download section of the site. When I try to open it pops up this error.

Data/enGB/wow-update-enGB-18273.MPQ: World of Warcraft can’t make a required change to an archive file. Be sure you have write permission for the World of Warcraft folder or try running the game in administrator mode. For more information, see: https://battle.net/support/article/6910

Tried to run it in Administrator mode, but it did not work. Any idea how to fix it?

Right click on your folder and uncheck Read only.