Connected to app to track?

I am newer to Swift foot pod and I got it so I could use it on my treadmill. When I am going on my treadmill however I do not need the swift app open. every time I navigate away from the swift app it no longer seems to track when I am doing. Do I need to have the app active in order for it to track?

Also, I’m more of a walker than a runner. but it seems the foot pod doesn’t have a setting lower than four as your average speed. Does this even work for walking?