You are interested in having Clarity Processes/GEL scripts make outbound SFTP pushes and pulls to a 3rd party application.
Release : 16.0
Component : PPMBPM
This is not possible. A third party middleware tool in your environment would be needed to pull or push files from Clarity through the SFTP directory.
Clarity can NOT make any SFTP requests in GCP.
Clarity only has access to the file directories on the SFTP site like local a file system.