What OS version are you using on your mobile? Do you have Acrobat app installed on your mobile device?
Is that ebook in pdf format?
9.0.2 iOS, yes I have the app downloaded and yes the eBook is in pdf
The PDF document shown in your screenshot above is a "protectedpdf" by Vitrium (not Adobe).
Unfortunately, Adobe Reader mobile apps (iOS, Android, and Windows Phone) do not support third-party DRM (Document Rights Management) protected PDF documents.
Please use the desktop version of Adobe Reader on a Windows or Mac computer to open the "protectedpdf". Sorry for the inconvenience.