If you are planning to email the document, you can merge the google doc URL field into a link in your email template to send a link to the google doc.
Or you can create a formula field that can create a URL to link to the google doc but will export to PDF upon clicking it. See this article for more information on this option. This will give you a link directly to download a PDF of the google doc when clicked. You can click and save the PDF if you want to send more manually and attached to the email. Also you can export to PDF within Google Doc under File. A5 Documents can’t send a PDF of that existing google doc out via email with PDF attached. It only does that when generating one from a template. It might be possible to use the existing google doc as the template to put in some button code to still use A5 Documents.
If you want to send the document for electronic signature, then use A5 Signature app to send the existing google doc for eSignature.
Here is an example of the URL format for a direct PDF download:
You need to place the google doc id where “FILE_ID” is.
Read this article on how to create a formula field from google doc full URL to extract only the google doc id.
If you have a url field called “Google_Doc_URL__c” saving the google doc id then this would be the formula to create this url:
"https://docs.google.com/document/d/"+ MID(Google_Doc_URL__c, find(‘/d/’,Google_Doc_URL__c)+
3, find(‘/edit’,Google_Doc_URL__c) – find(‘/d/’,Google_Doc_URL__c)- 3) +"/export?format=pdf"