Not redirect to file url

On my website I have download brochure button,
I want whenever a user click on this button a pop up will came after filling the details it’s redirect to dynamic file url (related to current listing).. All the things are working fine but after filling the form it’s not redirect. I am using that key value as a regular field in dynamic tag (link section)

For image field it is working fine but not for the pdf file..

Kindly help in it

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