First be aware there is an extra $40 service fee for that option ($45 for California filers.) You avoid that service fee by paying upfront with credit/debit card or a prepaid debit card you buy in a store. When paying out of refund, the refund must be large enough to pay for the product, the extra service fee, and any sales tax, if applicable.
If you do want to pay out of your refund, see this FAQ which lists the criteria to be eligible:
FAQ: Can I pay with my refund?
https://ttlc.intuit.com/turbotax-support/en-us/help-article/intuit-account-billing/deduct-turbotax-f...
