Those are different sites, you wouldn't have 8 routers in one place. So I guess each one of those devices can manage 5 unifi devices, going only by the image i

Those are different sites, you wouldn't have 8 routers in one place. So I guess each one of those devices can manage 5 unifi devices, going only by the image it looks like in their setup there is one AP for each device (if that is how the ui works).