The only legal way to obtain Battery 2 today is through a license transfer . If a previous owner sells their Battery 2 serial number, Native Instruments can transfer it to your account. Once transferred, you may be able to access legacy installers through your account's "My Products and Serials" page.

At its core, Battery 2 was celebrated for its clean, modular matrix interface. Unlike the rigid drum machines of the time, Battery 2 allowed users to customize their grid—up to 72 cells—each capable of holding multiple velocity layers. This flexibility was revolutionary for producers who needed to map complex, acoustic-style drum kits alongside synthesized electronic hits. The software introduced enhanced modulation capabilities and a more intuitive drag-and-drop workflow, which streamlined the process of kit building. The Sonic Library

Assuming you have the serial, you need the specific installer: