I am unable to open this software after down loading it. Keeps coming up with message @You need to extract from a previous volume to unpack Projca_2006.exe

Does anyone know where I can find this as i though after downloading all three files that would be it.
All help welcome.
Cheers

FS2004 (ACOF) - FS2004 Scenery
FS2004 Scenery--Project Canarias 2006