ADE is described as 'A timetabling, resource planning and management solution aimed at schools, universities, corporations and military training centers' and is an app in the Office & Productivity category. There are four alternatives to ADE for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and Self-Hosted solutions. The best alternative is Booked Scheduler. It's not free, so if you're looking for a free alternative, you could try Rapla. Other great apps like ADE are Celcat Timetabler (Paid) and Hub Planner (Paid).
Booked (formerly phpScheduleIt) is a simple but powerful reserve-anything scheduler. With flexible layouts, custom rules, a powerful administrative backend, and an unbelievably simple user experience, Booked can fit almost any need.