My name is Lilith, I'm on the Social Care team at Shopify.
I took a look at the site you linked. I do have the PayPal button show up for me on Chrome:
The Dynamic Checkout will default to showing your customers their preferred payment method, determined by their payment activity on other sites. As a side note, for PayPal, customers will need to be logged into PayPal to see the button.
If you don't personally use some of the payment methods that are associated with the Dynamic Checkout, you can still test to make sure they appear properly on your site. Here's a fantastic guide on how to test each payment button.
Let me know how you do with the information above! I'm happy to answer any questions you think of as you work on your business.