It seems to me that the problem you want to solve requires additional functionality. In this thread there is now a vote for the implementation of the necessary features: https://nintex.uservoice.com/forums/430063-5-nintex-workflow-cloud/suggestions/39948154-here-update-file-name-in-workflow
So this is not possible with the function "Convert document" ?
in the future the form will be linked to the agency's Active Directory so once someone starts typing in the project manager's email in the form, the email should be pulled from AD and autofilled. The workflow would then send the form to designated project manager whose email is the input in the form.
For testing purposes right now, I'm doing this from a sandbox environment within Sharepoint so I don't have access to the active directory, so what should I use to link the form's input to the workflow?
To clarify, are you using both Nintex Forms and Nintex Workflow or Nintex Forms and (OOB) SP Online Workflow?
Without knowing how your form is set up, I imagine you're recording the recipient in a field (be it text or person/group). Is it just a case of connecting this field to a column for the workflow to pick up on item creation/modify?