Hello! I am not an expert on this particular topic, but might be able to help you a little:
1. You need to create an app navigation link as explained here: https://help.qlik.com/en-US/sense/September2017/Subsystems/Hub/Content/LoadData/creating-OnDemand-app.htm
2. No extensions are required
3. ODAG is only available in QS Enterprice
4. Try with QS Enterprise
And most importantly, you first need to switch on the On-demand apps service in QMC.