Neutered/spayed rabbits can be introduced at any age by having them live side by side separated by fencing/pens. I personally do not put pet rabbits in cages, they need space to run and hop and just be rabbits.
I've always paired my rescues and have had success 99% of the time. Just give them time to become accustomed to each other.
I still can't figure out why anyone would have rabbits in the house and not have them neutered! They are so much happier and make much better pets when desexed but that's jmo.
They have articles on how to bond rabbits. I have had plenty of bonded rabbits over the years. Not all rabbits need a buddy but some really do like having one. Make sure both rabbits are spayed/neutered.
i keep all my females together in 3 large hutches/runs and have never had any probs. they r all breedable and different ages but if done right they can be kept together. my males r all seperated and does stay seperated till after kits r weened before going back in with herd pens. my females r always taken to the males to breed then pened by themselves.