Per USAA : 

In order to qualify for the available TurboTax discounts, you must access TurboTax through usaa.com before completing your tax return. There are links to TurboTax found throughout usaa.com where your discount will be applied when you submit your completed return to the IRS.

If you filed your return using TurboTax and accessed it via usaa.com and did not receive your discount, TurboTax will need to research your transaction. In order to do so, please contact the USAA tax line at 800-531-6347 and say "tax questions" at the main menu. Please be prepared with the following information:

TurboTax order number (can be found in your e-mail inbox)First and last nameComplete addressE-mail address used when signing into TurboTaxTelephone numberUSAA number

https://www.usaa.com/inet/wc/advice-tax-center?showtab=turbotax

Per TT :

How do I get my TurboTax affiliate partner discount?

To get your partner discount, make sure to prepare your taxes at the special TurboTax site provided by your bank, credit union, or insurance company – not at TurboTax.com, which charges the non-affiliate price.

1. Go to the special website provided by your bank, credit union, or insurance company and select the TurboTax link or icon.
   • This will take you to the special TurboTax-branded affiliate site with the discounted pricing.
2. Select your product, sign in, and start on your tax return.
3. When you get to the Review your order screen (in the File section) you'll see the discounted price along with the message Your discount has been applied.

Please note that our agents are unable to apply or issue refunds for affiliate discounts if the return was prepared at the regular TurboTax.com site.