I am looking to add either an excel doc attachment or a link to an excel doc to a custom form, Workflow would run like this:
• User clicks on link to Asana form
• Asana form attachments field contains a link to download the excel doc
• User fills out excel doc and attaches to the Asana form before submitting
This way the workflow can be assigned to stakeholder to action upon with all the info they need without needing an extra step subtask assigned to requester to download, fill out & attach the excel after the request is already submitted.
I would suggest putting a public link to a google drive, dropbox, box etc file for the user to export and fill out in the description of where you would like the filed uploaded. Another option is adding it as a media file to your website and adding the URL to the description.