Do I need to buy all the released updates to begin playing WoW?

There are only two purchasable items:

• A subscription, giving access to everything up to and including the Legion expansion;
• The newest expansion, Battle for Azeroth, which is sold seperately.

But use the Starter Edition first! You can download the game without purchasing anything. The starter edition stops your progress at level 20, but you can play as much as you want. If you enjoy the starter edition then subscribe to continue leveling.

These expansions are now part of the base game and not available for separate purchase: Burning Crusade, Wrath of the Lich King, Cataclysm, Mists of Pandaria, Warlords of Draenor, Legion.

You only need the core game to start playing. This gives you access to the 8 original races (No Draenei, Blood Elves, Worgen, or Goblins), and 9 original classes (No Death Knights), and a level cap of 60.

To reach level 70, you will need The Burning Crusade, level 80 requires Wrath of the Lich King, and Cataclysm unlocks level 85. Each subsequent expansion requires that you have the prior ones. It is not possible to install Cataclysm without Wrath, or Wrath without Burning Crusade.

After realease of BFA datadisk you need ONLY the newest datadisk and subscription. For example when you create new account, you will play first 20 level for free. When you want to continue to level 110 you need ONLY to have subscription. If you want to have content from BFA in your game and continue to level 120 you need buy this expansion.