If you are eligible the refund advance will be offered when you have completely finished your federal tax return by entering all of your income in 2023. When you are in the File section of the program and have a federal tax refund the refund advance will be available on Step 2.
See this TurboTax support FAQ for the refund advance - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-refund/refund-advance/L52Mg0G5u_US_en_US?uid=lr57a55g
How to get a Refund Advance - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-refund/refund-advance/L52Mg0G5u_US_en_US?uid=lr57a55g