well i have been playing ... now on day 250
i have pulled about 4 legendaries from day 1.
my first legendary pull was about day 190...
things start to ramp up later once you are stronger and now exactly what to do. It is confusing and very difficult at first. You absolutely don't have to pay though, i spent 13$ on the game and I am nearly on end game content.
You will never get the heroes you want thats just the way it is, i accept the fact that some heroes i will never touch, in fact alot of heroes i will never touch ... lol.