I'm a design student and I need to design an Ipad app. Now, I saw a tutorial that shows how to do it using the folio builder but I have Indesign CC2015, and the folio builder does not exist anymore.
How can I design an app and download it to my Ipad so I can show my work in class?
The feature you are looking for has been discontinued. It is only available at great cost for large enterprises.
You would have to use third party software like the one below that interfaces with InDesign to produce apps:
It could also be done as a web app using in5.
Not an app, but you can create documents using Publish Online (InDesign with animations etc) which is free with InDesign CC2015 and easy to use, they would look great on an iPad.
Lynda.com have an excellent new online video tutorial to show you how to use the feature:
You can get a 10-day free trial.