Don't listen to what some people say, you don't need to sign up or scan a QR code in order to play, that's just optional if you want to get some free rewards.
Besides that little rant. The game is actually quite fun although it does seem like one of those games where it will be popular for a week then everyone will forget but it's quite fun.
I would honestly say, just play it for the World Cup (Single Player) and with bots because from what I've gathered from PVP is that hardly anyone passes the ball and it ends up costing you the match.