Installing a large doggie door is simple. Each door comes with a template that you can use to mark out the hole. Measure twice, cut once. Make sure to cut the door or wall to the exact measurements, trim the edges of the cut, use filler to fill any gaps and attach each side of the door using the included fixings.
If you have a glass door, you’ll need to consult a glazier to cut a hole or provide a door panel with the hole already cut.