There are two different ways to do it depending on if you want to receive your default notifications for the match you want to subscribe to or if you want to set up custom notifications for that match.
The first step is go into the calendar and click the three dots next to the game you want notifications for.
From the menu that appears, press 'Follow' if you want your default notifications for the match. This video shows you how:
If you want custom notifications press 'Set Notifications' and then select 'Customise' to choose which notifications you want. Here is a video showing how to do it.