If you would like to read Adobe-DRM protected EPUB/PDF files in the Aldiko Book Reader, you first need to register an Adobe ID and password. You can go to Adobe's website here to register one: https://www.adobe.com/account/sign-in.adobedotcom.html
Then open the Aldiko Book Reader, select the navigation drawer indicator at the top left corner, select "About", tap on "Adobe DRM" and then enter the Adobe ID and password that you have just registered to authorize your Android device.
After that, put the EPUB/PDF files in the external SD card or internal storage of your Android device (this depends on the file structure of your Android device), open the Aldiko Book Reader, tap on the navigation drawer indicator icon at the top left corner, select “Files”. Locate the files that you would like to import into the Aldiko Book Reader, check the box next to each of them, then tap on the “Import” icon.