I have recently purchased a second hand Samsung Galaxy Tab A Lite 7" tablet for my phantom 4 drone. The tablet is running on android version 4.2.2 and I can not get the DJI GO 4 app from the playstore. It says that the device is not compatible with this app. How do i install the DJI GO 4 app onto my tablet?

The list of recommended tablets shows a 7"Galaxy  Tab A, but they put 2016 in brackets.  http://www.phantomhelp.com/tips/18/best-tabletsphones-for-dji-go

I did a quick look and see that the 2016 and newer Tabs have 1.5 Gigs of RAM.  Older ones only have 1 Gig of RAM..  If yours is pre 2016, then that's probably why it won't work.  

FWIW, I have a real old Galaxy Note 10.1...  It barely ran DJI Go...   I tried to install DJI Go4 and got the same "incompatible" message you got.