Issue
You have configured Acquia purge module on your Acquia enterprise application and are seeing an error in the status page which says -
PURGE: ACQUIA PLATFORM CDN
Platform CDN isn't yet configured, please contact Acquia Support to do this for you.Resolution
If you are getting the above error in the status page or while running a drush p-diagnostics, you can check the following -
1.) Do you have a platform CDN entitlement or was platform CDN configured for your application and is being used? If yes, please reach out to Acquia Support to correct this error.
2.) If you do not have a platform CDN entitlement and are not using platform CDN for the application, then - The error can occur if the Acquia Platform CDN (beta) purger has been added but you do not have Platform CDN currently set up. In this case you will need to remove the Acquia Platform CDN (beta) purger and just keep the default Acquia Cloud purger.
To check your setup, you can either run drush p-diagnostics or verify it from the site UI - /admin/config/development/performance/purge