Because she is 16 you will have to buy both federal and state. It would be a violation to a federal or state warden if both are not purchased. You can purchase online and print out the licence (It will have proof of purchase) and as DirtyBird said you would have 45 days to sign and affix the Federal Stamp. So she would be legal not to have the physical stamp (as long as you actually buy it). It will come in the mail in a couple weeks if you purchase from Maryland DNR website. Here's a link where to buy thru MD DNR https://compass.dnr.maryland.gov/dnrcompassportal although going to a store like Dicks would work just as well. Good luck on the youth hunt!