The Autochess game is an 8-player PvP game mode in DotA 2 which is a PC game and only esist in PC，so if you want play Autochess ,you must download STEAM first.https://store.steampowered.com/about/
the second step is download Dota2 game in STEAM which is a free game.you donot need pay any money on data2 and AutoChess.
the third step is launch dota2 game and find AutoChess at ARCADE .
You can find it in the homepage list because it is a hot mod now.
if you not find it , search it!.
Now you can play Dota Auto Chess!! enjoy it