Hello @RitaM85 ,
If the document exists in your Google Drive, then you can simply link to it in your email using the share URL Google provides for the file.
Inserting text links
Inserting image links
Inserting button links
If you're wanting to have the PDF as your actual email, keep in mind PDFs can't be directly embedded into the email - only linked to. Only the image versions can be directly embedded into the email; we auto-generate the first page if when you upload into your account's library. If you have links in the PDF or multiple pages, you'd either need to go with the standard PDF email route of encouraging your recipients to click and view the full document, or you'd need to recreate the PDF in the builder.
See also:
Avoiding image-only emails
... View more