AK to DtD
General advice: All theme park to Disney Spring bus trips require making a connection at a resort. In a few cases you can do one leg on foot (no pun intended).
Best advice: Take the first resort bus, except Contemporary, Wilderness, Polynesian or Floridian. At the resort, transfer to a Disney Springs bus. If you first took a Saratoga Springs bus and are headed to the eastern end of DS (Marketplace), you can get off at the Congress Park stop and walk the rest of the way. If you first took a Port Orleans bus you can optionally take a boat the rest of the way.
Most concise advice: See previous reply. Pop Century does not have multiple stops within the resort i.e. whether or not the bus you connect to will stop several more times before it comes out and heads for DS.
Fastest trip: Take a taxi.