While the original Caldera map is gone, a new free-to-play version of (formerly known as Warzone 2.0) is available and does not require a purchase of Modern Warfare or any other title. How to Download the Current Warzone on PC
The era of Warzone Caldera officially ended on , when Activision shut down the game servers permanently. This means that Warzone Caldera can no longer be downloaded or played on PC, even if you own Modern Warfare (2019) or previously played the standalone free-to-play version.
Call of Duty: Warzone Caldera Sunset FAQ - Activision Support
You can download the active version of Warzone for free through the following official platforms:
If you try to launch the game now, you will encounter a connection error as the servers are no longer live. Transitioning to the Current Warzone