It means the mender-binary-delta module is not installed on the device.
Mender-binary-delta can’t ordinarily be used with an image from mender-convert. It doesn’t mean it can’t work, but we don’t support it out of the box, and you need to take some care and make sure the image is prepared for running in read-only mode.
I would strongly recommend moving to a Yocto based build if you are planning to use mender-binary-delta. Then install mender-binary-delta following these instructions.