This is a standard php error telling you which required file is not able to be found, the path where it is not found, and the paths searched.
Check first to see if the file is indeed in the designated location. If the file is there, but not getting read, it is likely a permissions problem.
This is basic web dev stuff, unrelated to eZ - unless for some reason the installer is not installing files even with permissions set correctly. Not likely with the number of successful installations out there.