I don't know if someone already posted this or not; but after I downloaded BA 2.0, I couldn't figure out how to install it, so when I first saved it, it would be in Gamedata/addon. Would that work, because when I downloaded the first time, I found the file, and double clicked it, but it wouldn't do anything. Now that the download is done, it won't let me use 7zip, because of its unknown filetype. I can't seem to find an installer, either.

try to add an .exe or .zip or .rar extension and see if you can open it then

CommanderFixer wrote:...Now that the download is done, it won't let me use 7zip, because of its unknown filetype. I can't seem to find an installer, either.

If you downloaded it from Filefront and there is no extension then it is most likely an .exe file, from what i've seen so far the changes Filefront made to their servers did not affect the .7z, .zip or .rar files only executable/self extracting archives.
This has been discussed before.