My name is Lilith, I'm on the Social Care team at Shopify.
Thanks for adding that screenshot, that's really helpful for us to see the error!
Normally this red banner comes up when a payment method is failing. With the payment method, you're using on your account to pay the bills for your subscription you may be having some obstacles with your payment. You can check on which method you're using by going to Settings > Billing. In there you can either replace your credit card or you can also disable and connect a new PayPal account as shown below.
In most cases, the issue can be from insufficient funds on a credit card or PayPal. It can also be due to a problem directly with a credit card or the PayPal account itself.
I'd recommend checking on or contacting your credit card provider or PayPal to determine what might be limiting your purchases.
I can also take a closer look to see what the exact error message is on our side for you. Let me know if this is something you'd like me to do and I'll send over a secure email to you to authenticate and continue the conversation via secure email.
I did notice that the domain that you're trying to purchase in your screenshot has two letter "h"s. Just wanting to make sure that you're purchasing the domain you intended and not a typo.
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.