In addition to buy a hunting license in Maryland, you must present a Certificate of Competency in Firearms and Hunting Safety. This is required of all first-time hunters. If you hunted on private property prior to July 1, 1977 and have certification to prove this, you don't need proof of the safety course. You may also omit such proof if you held a hunting license prior to July 1, 1977 and have certification to prove it. Lastly, you may omit proof of the safety course if you are buying an out of state license and plan to only hunt waterfowl.
Check out these Frederick, MD Hunting resources: