It needs to be secure top and bottom. So the floor needs to either be on concrete/pavers, or there should be a hardware mesh buried under the ground if it is to be on fresh lawn.
The top (including any runs) need to have solid roofing or areas with wire to prevent critters from climbing over and to prevent birds of prey from swooping down.
Here's a sample of an outdoor hutch with attached run (which they always have access to). They are also let out in the larger fenced yard when supervised. You can see how they've had to cover the main hutch in foul weather.