I’m not 100% sure about your question, but I think you’re asking how can you add a download link to your thank you page once someone has signed up to your list by giving out a free product on a landing page.
If so, you will have to host the product yourself, either via a server, Google Drive, OneDrive, DropBox, etc and then simply copy and paste the URL on your thank you page.
That way, when your new subscriber has signed up successfully when they arrive on the thank you page, they will be able to download the product.
I hope this helps.
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