Yep this game is based off Defense of the Ancients, a Warcraft 3 Custom Game. DotA games took hours sometimes, so they've actually really shortened the time games take in this. If you're not sure you're gonna have 30-60 minutes to play a game, I wouldn't start it.
And about being "banned", it just says you've been banned from that particular lobby because the host kicked you. Once you get to level 5 and higher people will stop kicking you so often, they just do that because you're new.
What you should do is host a 6v6/3v3 compstomp where you and a couple other people play against a team of all bots on the "New Player" difficulty.