This RGBW LED tape driver provides 8 outputs of RGBW. Therefore, the simplest way to control this using ONYX, is to simply patch 8 RGBW fixtures. These can be found in Patch > Commands > New Fixture > Generic Colors > RGBW > Virtual Dimmer: ON…
If you are only using the first 2 RGBW outputs from the driver, you could just patch 2 RGBW fixtures into ONYX. The DMX address of the first RGBW fixture you are patching, must match the DMX address of the RGBW LED decoder. If the RGBW LED decoder has an 8bit/16bit setting, set it to 8bit for simple operation.