I have tried to buy a sourcebook but the cart won’t let me scroll down to complete the payment. However, when I go to subscribe and the payment comes up, it has the button for ‘Checkout’, which it doesn’t for me when I try to buy a sourcebook.
I was just wondering as I have never had to subscribe before on an app to buy source material, i.e. D&D Beyond.
You don’t have to subscribe to buy books.
If you’re trying to make the sourcebook purchase on a mobile device, we’re aware of an intermittent issue with scrolling in the checkout flow and are working on a fix. If you login from a computer, you should be able to checkout without issue. 
Hi,
I am still having trouble scrolling to checkout and I am on my laptop. I did try it on my phone and had the same issue, though it sounds like your aware of that one.
That’s good to know, thank-you
Why don’t you send us a support ticket and we can take a closer look at what’s happening for you and get this fixed.