This is my recommendation for your question. You can change your code to:
<a href="/cart" class="purchase button" id="add">GET THE JOURNAL</a>
Please try this and let me know if you need further support from us.
Hope this helps!
Thank you for your response. The code still does not seem to work: I think the code you provided redirects to the cart, but since this button is going to be on a regular page (not a product page), it doesn't add anything to the cart. I need it to add a specific product to the cart when you push the button, so that's the part that I'm stuck on.