steam won't work

MacBook Pro (Retina, 13-inch, 2015)

So I downloaded steam and installed it. But when I try to open the Steam application, it just freezes, on the first steam screen picture and wouldn't load the program at all (See the screenshot). I have tried to delete and reinstall steam, but nothing happens. My question is; Am I doing something wrong or are there some program that you have to install alongside steam to run it??Any help?