I have over 800 Adobe .pdf files on my Sansung Galaxy S4 and when I try to open one it wants a password. I have no idea, first of all where these documents came from as I can't open them, what that password might be. Does anyone have any ideas for me? I asked at Verizon and they just shrugged their shoulders. Not what you want to hear from your cell phone provider.
There's really not much we can tell you other than somehow you got a hold of a password protected pdf. There's no way to open it without the password. If you don't know what it is or need it, delete it.