I super love "playing" Zombies, Run! - the story missions are fun and are getting me outside and exercising, which is super cool.
Ideally, I would like to alternate my story runs with supply runs to make the story missions last longer, as it were, but when I looked at the mission list earlier today in order to figure out what mission I wanted to run tomorrow, I noticed the supply missions are still locked.
When do they unlock? Is it at some point during the story? Or do I have to do something like complete the whole story?