When in the drafting screen, click on Use a Template, navigate to the Google Docs template and click on it.
You can see which one is a Google Docs template through the triangle symbol before the template name.
Once your document is uploaded, you can rename it or add a deal value to it (recommended if it's a sales document). You can then add your recipient(s).
Edit a GoogleDocs template in draft
Once the template is uploaded, you can edit it to suit your specific recipient.
Click the Edit button with GoogleDocs in the upper right corner above the document.
A separate window will appear and you can edit the template just like in GoogleDocs.
You can also choose to open a new tab for easier editing.
When you are done, click the Save button to make the changes to the document.
Add more resources to the draft
If you would like to upload another block with content, scroll below the already added page and repeat the process; choosing from the Upload a File, Editor, Use Template, Video, Link, or Google Drive.
If you want to upload another editable block to the already existing GoogleDocs draft, make sure all blocks don't need to be edited. If you have two different editable blocks to the same draft and you edit the GoogleDocs draft, all blocks will be overwritten with the newly edited GoogleDocs document.