you answered immediately without reading the link...
what about first reading carefully the basics?
SAF = Storage Access Framework
I'm assuming you are talking about an non removable (emulated) sdcard...
for older devices afaik this still should work (I might be wrong, but I'm sure, @Anke will correct me then 
)
set the default file scope in the project properties to Legacy
and for the image try this full path
file:///storage/emulated/0/MyPicture.jpg
for the file component set the file scope of the file component to Legacy and try
file:///storage/emulated/0/MyText.txt
Taifun