We are looking for a solution for project management pipeline to send out creative PDFs to a client to proof/make changes. When client makes the changes or signs off on proof we would like that to trigger the pipeline to continue and notify a user/designer. 

Is there any integration with Zoho and proofing  ?  Our clients would not have access into zoho. 

GoProof.Net is one of the proofing softwares that we currently use for external proofing.