If the order payment has failed, there could be several reasons for that - let's go over the recommended troubleshooting steps.
Use the "Retry" button
Click on the "Retry" button next to the order - most likely, the payment will go through this time.
Check if a payment method (or balance) has been added
Navigate to the Payments section of your Printify account to check.
Check if there are enough funds available on the card (or in the balance)
If you're positive that a card has been added to your Printify account, check whether there are enough funds available. If so - you may want to try using an alternate credit/debit card or contact your bank to determine why the payment is being declined.