If you want to find a quick answer do what I do:
GIVE UP. Buy a NowTV stick mine was £20. Annoying but I assume the TV channels license their app to the highest bidding manufacturer. My Samsung TV has the app but not the Panasonic.
Buy an Amazon fire stick or as @Fastrack1966 suggested buy a NOW stick.
Prime day is coming, so you will get a fire stick for cheap no doubt.