I have not really done any work on the version that was for OMV 2.x, besides seeing that it downloads packages with correct links. I really don't want to waste any time on it. I will try to make sure the OMV 3.x version is working properly. It has not been ported to OMV 3.15 plus as of yet.
If I remember correctly there was some issue on your system with the unzipping of the gzip file using the tar command. I am not sure if this is issue with your system or not.