Explore this site for the airport and look for parking information, terminal maps, arrival/departure maps, baggage claim areas.
http://www.orlandoairports.net/
Have them check your flight's arrival times on their smart phone, if they have one, about an hour before they are due to pick you up. If they print out the airport's maps they will feel better able to navigate the area. Maybe they can even make a trial run if they have maps.
Enjoy your visit!
Jan in VA