To get Octane Render for Cinema 4D R25, you can use the edition , which is a free "Prime" tier offered by OTOY for both Windows and macOS users. This version is limited to rendering on a single GPU but provides a great entry point for learners. How to Access and Install Octane for C4D R25 OctaneRender for CINEMA 4D Installation Guide (macOS)

If the render is free, you’re the one being rendered.

While a completely "free" full version of OctaneRender for Cinema 4D R25 doesn't exist legally, the and official trials are excellent ways to get started. By using the official software, you ensure that your renders are stable and your workstation remains secure.

The C4D plugin relies on the Octane Standalone engine.

What is the correct Octane Render installation setup for Cinema 4D?