Hey @Billseng Kristen actually outlined the only method I could think of to achieve this too!
Unfortunately sequences doesn’t support email attachments, the file itself is associated with the contact record via the logged email, but this data isn’t really available outside of the timeline. Sequences really only supports personalization tokens, which are essentially just property values that will auto populate, the same thing as a merge tag. So if you had a url within the contact property for the quote you could reference this as Kristen mentioned, but outside of that I don’t believe there’s any out of the box way to achieve this!