Acrobat Reader on Samsung Tablet won’t open .PDF files directly from File Viewer or email

When my wife clicks on a PDF attached to an email or shown in the file viewer on our NAS Drive, Adobe Acrobat pops up but does not show the file, instead it shows pay Servives from Adobe and a list of PDFs in downloads to select from.  
 

We first have to copy the file to the Downloads folder then click on it, then select it from the file list shown on the home page of Acrobat before viewing the file.

how can we make Adobe Viewer open the file directly from file viewer or an email  like in Windows.