If you download it, don't join the first lobby you see.
My advice is to watch some videos on youtube, play some games solo, then look for new player lobbies or create your own and set restrictions on it.
It only takes one player on the enemy team who regularly plays the game and you'll get stream rolled.
Or you'll join a game of regular players, can't hold your lane and everyone will get frustrated when their base is blown up from your lane not holding.