PWS follows the OSS Cloud Foundry, which is different from PCF. It also is updated quite often so gets new features very quickly. The additions to VCAP_APPLICATION were recent additions to CAPI.
https://github.com/cloudfoundry/capi-release/releases/tag/1.83.0
You'd need a PCF release that contains at least 1.83.0 CAPI. At present, PCF 2.6.0 is at 1.80.0.
https://docs.pivotal.io/pivotalcf/2-6/pcf-release-notes/runtime-rn.html#2.6.0
Hope that helps!