Allthough on a map it seems hard to reach Baarlo, it actually is quite easy. There are a few airports that are within 1 hour drive from Baarlo. From the train station Venlo and Roermond, a bus will drive directly to Baarlo. So you do have many options, check them out and plan your trip.
Within a distance of 100-200 km from Baarlo, there are several airports. From any airport you can rent a car, grab a taxi or take the train & bus. Check out the airport websites for flight information, many low-cost airlines fly to one or more airports listed on the map.
Baarlo is easy to reach by car. From Maastricht, Eindhoven or Nijmegen take the exit to the N273 and you will drive to Baarlo.
If you travel by car and you are not staying at Castle de Berckt, there are several parking places in Baarlo. Keep in mind, you are not able to park the car in front of the venue! These spots are reserved for the bands and the crew of PP Europe.
If you take the train (from the airport for example), travel to the railwaystation of Venlo. From Venlo you can take the bus to Baarlo. You can also go to the railway station of Roermond but Venlo is closer.