Unless some significant changes have taken place, sourcing the item you seek is fairly unlikely.
The best thing you could hope for is that somebody else has simply removed a similar unit and left the cabling behind in error, but again unlikely.
Only remaining option is to ask if you can return the unit as really not much use to anybody without the ability to hook-up to a vehicle.
Sorry its predominantly bad news, but a word with the guys on here may help. The guys I would contact are :
Holland 314.
Mickyboy.
And finally, anybody on the ICE pages of this forum.
Maybe this but suspect they will require a quantity purchase.........
https://www.connect2t.co.uk/wiring-l...IaAo58EALw_wcB
Hope somebody can help you out !