Can you put this lock on a larson door that doesn't have one now ?

The QuickFit handle set is designed for use with new Tradewinds and Signature series doors that come with the QuickFit lockbody. It is not for use as a replacement handle set or older doors. If you need a replacement handle set, your local Lowes store can help you find the right handle set for your door. Just let them know your model and age of door and they can help you get the replacement handle set.