When photos are uploaded to zenfolio the Title, Caption, Copyright and Keywords are read from the IPTC data. Unfortunately Darktable does not set these values on export. Zenify is a bash script that will (using imtag) extract the metadata as set by Darktable and copy it to the appropriate locations so that Zenfolio will find it when the photos are uploaded.
Zenify should update the metadata to match what is done by eogMetaEdit. In a nutshell, Darktable export sets:
Zenify will copy the values to the appropriate Iptc fields:
Zenify will also set Exif.Image.Make/Model and delete the same meta variables as eogMetaEdit.
Zenify should be run on files exported from Darktable before they are uploaded to Zenfolio.