A door with an existing deadbolt installed is easy to replace. In most all cases no drilling is necessary.
On the interior of the door there should be two phillips head screws and two screws on the bolt latch holding it in the door. (You can see this by opening the door and looking at the edge of the door.
Remove the screws from the deadbolt and the latch and install your new hardware in the reverse order your original hardware was removed.
Don’t over tighten the deadbolt screws or the deadbolt latch screws until you have operated the deadbolt a few times with the door open. This makes sure everything is properly aligned when you tighten it down.