Auto Upload Invoices from Books/CRM and docs from Sign

So I have the Workdrive/CRM integration and I love how it creates folders for each contact, lead, deal etc. but I would really like the ability to auto-upload standard docs that each client has that generate through Zoho services such as PDFs of invoices and completed Zoho Sign documents.

I don't see a Workdrive integration with Zoho Books or Sign nor an ability/action to upload these files through Zoho Flow or Zapier. I'd prefer them to go to their respective contact/lead/deal folder automatically but at minimum I at least need them to be auto-uploaded to a generic folder for all "invoices" or "signed docs" without having to upload each file manually each time an invoice is created/paid or an agreement is signed.

Any solutions available for this? I would think auto-uploading invoices and signed documents would be pretty run of the mill.