Hi Mary,
Ok first of you need to assign a CLASS to your Button element, so we can use those button as the Modal Popup trigger. To do this, inspect those button element and under the customize tab add them a CLASS.
Use a common class if these buttons trigger just one form, or use a unique class if these buttons need to show a separate form each.
Then on your Modal Popup settings under Behavior > Manual Display > Launch With CSS Class add the Class of your button.
<br/ >
Now this will make your button trigger the Modal Popup, the last thing to do is redirect the user to a “Thank you” page (once they sign up) which contains the download URL. To do this in the Modal Popup under Submission on the Successful Submission option set to Redirect User then paste your “Thank you” page URL on the Redirect URL field.
Now if you dont want to send the user to a thank you page and just send him straight the download file, set the Redirect User To field to Download File, and paste your download file URL on the Redirect URL field.
Sorry if this is kind of confusing with those fields name almost redundant, but the screenshot should able to help you understand what I mean.
Hope that helps,
Cheers!