Rabbits can be litter trained. You need a little patience and the right bedding. Spayed or neutered rabbits are much more successful at litter training, since they don’t have the desire to mark their territory.
The key is to use organic litter, such as unscented Carefresh bedding. Other brands are available. Do not use pine or cedar bedding, which have aromatic oils that can cause respiratory irritations and lead to infections. Clay litters and clumping litters have dust that can also cause respiratory infections. If you prefer to use wood chips, aspen chips are okay.