You will need to click the 3 lines at the top of the page, click on Platforms, and then click on MetaTrader4 or MetaTrader5.

Then scroll down a little until you find MetaTrader all devices and click on Mac (If you are using an iPhone/iPad, click App Store.

The MetaTrader website suggests:

Play on Mac: Click here and follow the instructions.

Live server details are:     
Demo account details are:

We do not officially support Play on Mac.