fanamotaung,
As of today (August 10, 2014), the latest version of Adobe Reader is 11.3.2, which runs only on iOS 7. 10.1.0 is the very first version of Adobe Reader for iOS released back in October 2011. It is rather obsolete and does not provide the support for form filling.
If the operating system of your iPad 4 is iOS 5 or 6, you will get a dialog like this when you try to install Adobe Reader from the App Store.
Image may be NSFW.
Clik here to view.
You can tap the Download button to install an older version of Adobe Reader for iOS.
However, we'd highly recommend updating your operating system to the latest iOS 7.1.2 and installing the latest version of Adobe Reader (unless you have a reason why you do not want to update iOS).
Once you install Adobe Reader for iOS, you can launch it and tap Help in the Reader home screen to see the in-app Handbook (Help documentation), It has a lot of useful information to get you started on Adobe Reader for iOS.
Please let us know if you have additional questions.
