Welcome to Android Central! The manual doesn't mention anything about the clipboard access from the Samsung Keyboard that is available on other Samsung phones: http://downloadcenter.samsung.com/c...P_Galaxy-J7_EN_UM_MM_6.0_042516_FINAL_WAC.pdf. You're saying that you've already tried the key just to the left of the spacebar (which would give clipboard access in other Samsung phones)?
Usually long pressing on any typing space (such as this for example) should pop the clipboard up. Failing that, find the dial pad and long press on the empty space above the numbers..
You won't find clipboard in settings.