On the bottom bar of your app, you'll see a tab that says PRO. From there, click SYSTEMS at the top of the page.
There, you will see a list of systems that will be sorted by the number of current picks. You can also click on the dropdown menu in the top left corner of the page to filter which sport you are looking for.
When you see a system you like, click on it to see a more detailed description. From there, click "ADD TO MY SYSTEMS" to receive plays and alerts on system matches.