The Apple TV app is available on iPhone, iPad, Mac, Apple TV set-top boxes, smart TVs (Samsung, LG, Sony, Vizio), gaming consoles (PlayStation, Xbox), and streaming devices (Roku, Fire TV). MLS Season Pass is accessed through the app.
You can also watch through a web browser at tv.apple.com. The app is free to download; the MLS Season Pass subscription is separate. All 34 regular-season matches per team, plus playoffs and MLS Cup, are available.