Anyone else having trouble getting it to download?

So, since my desktop is broken, I downloaded steam onto a laptop, and am trying to download Terraria. Unfortunately, when I do, a popup comes up and it doesn't seem to want to go anywhere. I can click cancel, and have a few times because it didn't seem to be doing anything, but I also can't download Terraria. The popup is just a box that says just says "scanning for steam games updates...", and prevents me from clicking anywhere on the screen. It just sits there and looks like it's loading something, but I think it's stuck in some sort of loop.

Is this thing necessary for downloading Terraria? And if not, is there a way I can get past this?