The man coverage thing was a change to the way the game handled uncovered pass catchers.
Xavori did a good job explaining how you make zone work.
Step 1 is picking the plays in your playbook.
In your playbook, you can pick man or zone plays. Make sure you actually have selected 'zone' plays if you're adding the zone roll. In each category, the plays that are blitzes say Blitz on the image. Under the plays you select, there is a little description that tells you the depth of the play (short, medium, long) and if it's a pass, run inside or run outside play. You need to pay attention to all of that information.
Step 2 is setting your tactics to match your playbook.
-If you have no zone plays you need to set zone to 0 or when that rolls, the sim will pick a random play for you. If you have no man, you need zone at 100.
-Then you look at your blitz plays and pick how frequently they will fire in those situations.
-Finally you look at the play descriptions. If you have all medium, plays in your playbook, you shouldn't be calling short or long stuff or again, you'll get random plays picked by the sim and not by you.
