The obvious question is have you contacted the seller? Can you post some pictures maybe that would help some money figure out how to connect it.
I just checked by doing a search and found a YouTube video on how to connect the Datex2:
View: https://youtu.be/pvumfnCff10
The video talks about the advantages to using the device, but not the connections. For that I followed the link in the video description to the Datex II Site. The connection are simple, the two outside xt60s are for the batteries, the connection to the bike/controller in the connector in the middle next to battery connector on the left holding the device with connectors facing up. Check the attached diagram.