The short answer is Yes! You can add attachments to any meeting type except a Quick Meeting.
To add an attachment to a meeting, click Attachments.
From the Attachments view, click Add Attachments. Any user with an an Instant Agenda account can upload a file that is 100 MBs or less. Meeting guests can't upload files.
Any meeting attendee, including guests can download meeting attachments.
If you cannot upload your file, you can add a link to an external file (Google Doc, Sharepoint, etc). Just paste a link into a topic name or description. It will automatically be turned into a clickable link.