Hi @Leslie Nicole,
Thank you for sharing your question with us. This is a great question.
We actually have a way in Klaviyo to get the best of both worlds! You can add a URL to your welcome email that both applies a coupon code and re-directs the user back to your website. For more details on how to get this set-up in your welcome email, check out our guide here. I am also including our guide on using Shopify coupons in Klaviyo in general here.
When it comes to attachments, we also have a guide that will allow you to link users directly to a file of your choosing.You can find our guide to this here.
With respect to getting the welcome email instantly, by default the user will have to confirm their subscription as per our double opt-in process in Klaviyo. Only after they confirm, will they be added to the list and receive the flow email containing the link and/or discount code. If you’d like users to forgo this double opt-in step entirely, and get added directly to the list and trigger the flow immediately upon filling the form, see our guide on enabling single opt-in for your list.
Hope that is helpful and thanks for being a member of our Community!