Can't get SIMS 4 to install on Mac

My specs are:

macOS Sierra

Version 10.12.6

Processor - 3.1 GHz Intel Core i5

Memory - 8 GB 1333 MHz DDR3

Graphics - AMD Radeon HD 6970M 2048 MB

I purchased SIMS 4 through steam but it is giving me the "wrong platform" error code when I try to install.  I tried to launch through Origin but the game icon is greyed out. I can't do it from there either. After researching it, it appears this game should work on my setup. What am I missing and how do I fix it?

Thanks!