there are metal doors, BUT they are NOT solid metal. They have a metal skin on all sides and insulation blown in side for security and insulation and noise reduction. If so, yes you definately can install a dead bolt in that door. First, you need a 3/8 inch drill. Then you need your dead bolt with a template. determine the width of the door and use that measurement on the template. Mark the side holes and the front dead bolt hole. Before doing this, if you have a storm door, make sure that when the dead bolt is installed that it does not line up with the storm door handle. If you do the storm door will not secure because the handle hits the dead bolt mech.
Now, go to a home center and get a dead bolt cutting round drill bit. There are two kinds, one for wood and one for both wood and metal skined doors. Do not get the wood one. Then you will need the appropriate paddle bit for the side mechanism. You can get a kit with all this in it, but again, a metal drill hole boring bit.
Make sure that you get a throw on the dead bolt that is real deap, cheap ones only go 1/4 inch into the side jamb. I like an extra long one so that I get that throw into something solid other than the side jamb only.