I want to set this application to start downloading 30 min every hour. Is there a possibility to do that?
Yes, it's possible to do that using the Periodic synchronization feature. Launch Internet Download Manager and click on the Scheduler option. Create a new queue and use the instructions from the image below:
Additionally, use the information found on the official website to learn more: http://www.internetdownloadmanager.com/support/schedulerD.html