This product does so many things. I started out needing scheduling tool but a year later I was loving the project management tool also. My creative/marketing dept uses it for review and approval for our ad campaigns. The subscription price is cheap and customer support is five star.
Easy to manage many users. Each person only sees their assignment, schedules, files etc.
No app but frankly the actions I need to do are not really suitable in an app. BTW I can log in from any smart device.