Did you download the correct installer?
If you have Prepar 4 you need the Installer for Prepar 4.4+ AND you need to check that you have at least Prepar 4.4 installed (4.3 would not work, because PBR is there since 4.4)
If you have FSX or Prepar 3 you should use that installer (and also check that you have the LATEST Prepar 3 installed, it would not work with early Prepar 3 installations.