Samsung Tab A Marshmallow doesn't show contents on SD card
What you see, that it not your external sdcard, but your internal sdcard:
/storage/emulated/0/
This is the storage your phone brings, when you have no external (removable) sdcard in it. Don't mix it up.

Under Android 6 this external sd is usually in a path like, e.g.:
/storage/1234-ABCD/
where "1234-ABCD" is an arbitrary number of the individual removable sdcard.
So try to open the external sdcard with your file explorer by going up two folder levels from /storage/emulated/0 and then you will find your data.

Maybe you try as file explorer the free app Total Commander which is very mighty and can help you find things.

By the way: under Marshmallow you need to allow explicitly each app, which is not a system app, to read the external sd-card. And writing it is another thing and even more difficult, as the app itself needs to bring the support for it (different from Android 5 though!).
But with your internal file explorer (this is a system app) there should be no problems to read the external, removable sd-card, you just need to go up the path.