If you open a pdf file it will have a different Adobe icon and it works
fine for me. If you try to open a non-adobe file which it sounds like you
are doing, it comes up with a different icon saying you need to sign in to
use the free version. I did not try this since I have two other free apps
(Kingsoft Office, and Polaris Viewer) to open other file types. They also
open pdf files. Perhaps you should download one of these other apps. Good
Luck!
Andrea