If it requires refrigeration, I wouldn't have accepted delivery in the first place. I always insist, often to the driver's irritation, on inspecting parcels before signing, whether for me or a neighbour. If it's damaged in transit, I want to know that before signing. Given that you have accepted it, can you contact the neighbour (mobile number)? If so, do so and dump the problem on him or her.
If not, all you can do is what you have done, and leave it in the coldest part of the house, and stick a large notice on your neighbours door saying your have a parcel requiring refrigeration for him, please collect ASAP.