They should have hardware with them. They will screw into siding or into concrete anchor bolts if brick.
Basically, you don’t attach the shutters to the windows, but to the house, either to the inside or outside of the window frames. Houses with shutters meant to keep out wind and rain are different from ornamental or decorative shutters. Storm shutters usually have much deeper frames to fit into. Today, without employees to run around securing shutters from outside, many shutters are placed inside and are locked from inside to give them strength. But most new shutters are attached permanently to the outside of the house, and are never closed or locked. But shutters can make your house look much more expensive. Best wishes, Jewell
Shutter spikes is one type of fastener.
Shutter screws or Shutter-Lok patented fastening system makes installation fast and easy. Holds in any material: vinyl, stucco, brick, fiber cement. Durable copolymer construction features molded-through color so that there is no paint to ever scratch, flake or fade.