You cannot legally download the FIFA 16 PC demo today. Your best bet is to buy the full game cheaply (e.g., via a used key from a reputable seller like Green Man Gaming or Amazon), or play a newer FIFA demo (FIFA 23 or EA Sports FC 24 have demos on Steam/EA App).

I couldn’t find a direct, official article from EA about a "demo FIFA 16 PC download" because for that game. The game was released in 2015, and its demo was removed from official stores (like Origin, now EA App) years ago.