Hi John, maybe this way:
- push button opens a colorbox (.inline) which loads a hidden div.
- in the hidden div is the email field
- after filling the field, the dl button will displayed
Could you also do without colorbox.
- click on dl button shows the email field
- after filling the field, the dl button will displayed
dl button should first save the emailaddress and then call the download.
I think mpform can handle conditional fields.
With miniform it is also possible with your own code.
I don't know a ready solution.