You assume that this image is intended to be used inside of MetaROUTER. But it is not. This image is for installing directly to the RouterBOARD, to replace RouterOS completely. The OpenWRT developers do not publish any official images that work within MetaROUTER. You would need to find somebody who has independently developed a Barrier Breaker build that has the MikroTik MetaROUTER guest patches integrated within it. I would check the “Metarouter images” thread in this very forum.
– Nathan