The official source is Native Access (now Native Access 2).

The Battery 4 Factory Library Does Not Appear in the Software

Sign in with the Native Instruments account used to purchase the software.

Ensure Battery 4 has "Full Disk Access" in your macOS System Settings under Privacy & Security .

The library is not available as a direct web download; it is managed via the ecosystem.

The Battery 4 Factory Library Does Not Appear in the Software