we cannot download Direct TV on our 1st Gen Amazon Fire Stick

I asked this Q before but cannot seem to find the thread.  We have a Gen 1 Firestick W87CUN.  Despite updating lates software, we still cannot connect Direct TV Streaming.  We get all the way to selecting the App then the App install highlights a box saying "unavailable".  AT&T tech just left the house on another matter and he too could not get it.   Is the Gen 1 that I have too outdated?