Both routes to WDW from the airport have tolls.
The best route to Pop is the southern route.
From the airport, take the South exit.
Turn onto SR417 (Central Florida Greenway) westbound. Proceed about 15 miles. NOTE: There are about 3 tolls, total about $3, along SR417.
Take Exit 3 onto Osceola Parkway westbound. Proceed about 1.5 miles, passing through the International Drive intersection and the I-4 interchange.
Turn right onto Victory Way. The entrance to Pop Century will be just ahead on the right.
Total travel time is generally about 25-35 minutes, depending on traffic and the mean average lead content of the driver's right foot.
Here is a Bing Map collection with driving routes from the airport to WDW highlighted; these routes actually go to Downtown Disney, so the ends are a little different than the directions above, but they will still get you there.
Bing Map - Driving Routes to WDW