Apps I didn't download requesting to be installed on macbook pro?

Ok, so I recently purchased a new macbook pro and a WD 2TB external hard drive. I do a lot of music production and when I was downloading some virtual instruments to my external hard drive, I noticed that there was another user in the "shared" section in My Computer. I didn't know what it was, so I kept resuming. However, the next day, I was downloading some VSTs from an extremely trust worthy site and I came back to check on my download and there was a "Word Builder PLAY" installer open requesting to be installed on my Macbook. I searched in My Computer and found a "Word Builder.PKG"...anyone have any thoughts on this? Could this be someone accessing my computer remotely or a virus? Thanks!