I doubt you are trying to open a PDF file because there is no authorization of the device.
Adobe offers a program called Digital Editions that requires authorization of the computer on which it is installed and then that authorized computer can authorize mobile devices that are connected to the computer and Digital Editions access it.
Digital Editions Home
What application are you trying to use to read your ebook?
There are many ebook reading applications that work with the Adobe DRM system on Android.
- Bluefire Reader - Android Apps on Google Play
- Aldiko Book Reader - Android Apps on Google Play
- DL Reader : DL Reader - Android Apps on Google Play (To be fair, I work for Datalogics and have helped build this ebook reading application for Android)
- and many more readers for Android : Books & Reference - Android Apps on Google Play