If you’ve recently started using Salesforce.com or have not used the Notes & Attachments feature of the platform, you might not immediately see the documents that are created by Formstack.
To see all attachments on a record, ensure that the Notes & Attachments related list is added to each of your page layouts. To do this, click on Setup, open the Object Manager and select the Object you'll be using. From the left panel, select Page Layouts.
Click on the Related Lists section and drag the Notes & Attachments Related List into the Page Layout if it is not already there.
Save the Page Layout.