I have a $96 Apple gift card redeemed and I can’t make any purchases with it

i have $96 balance

If you have enough money in your Apple Account balance, all you have to do is -> you need to set your Apple Account balance as your default payment.

See -> Add a payment method to your Apple ID

Add a payment method to your Apple ID – Apple Support (UK)

See -> What you can buy with your Apple Gift Card or Apple Account balance

What you can buy with your Apple Gift Card or Apple Account balance – Apple Support (UK)

and ⤵️

• You can't use your Apple Account balance to send gifts or gift cards.
• If you use Family Sharing, your family members can't spend your Apple Account balance. Funds that you add to your Apple Account balance are only available to you. Find out more about how purchases are billed to your Apple Account balance.
• Some purchases might require you to have a credit card on file, even if you use your Apple Account balance to make the purchase.

Get support from Apple directly -> Get Support or call Apple in your region see -> Contact Apple for support and service 

See -> Add a payment method to your Apple ID

Add a payment method to your Apple ID – Apple Support (UK)

Yes, You can have a credit card / debit card on file and an Apple Account balance.

👉 If you have set your Apple Account balance as your default payment method, your default payment method will be used first by Apple when you need to make a payment.

So see again -> Add a payment method to your Apple ID

Add a payment method to your Apple ID – Apple Support (UK)

See -> Remove a payment method from your Apple ID

Remove a payment method from your Apple ID - Apple Support

⤵️

If you can't remove a payment method

If you have subscriptions like iCloud+, have an unpaid balance, or you use purchase sharing, you must keep at least one payment method on file.

• Do you have a subscription? You can cancel iCloud+ and cancel other subscriptions from Apple. When your subscription period is over, remove your payment method.
• If you're in a Family Sharing group and you use purchase sharing, the family organizer must have a payment method on file. If you're the family organizer, turn off purchase sharing, then remove the payment method.
• If you have an unpaid balance, you might not be able to remove a payment method. Instead, change your payment method.
• 👉 👉 If you still can't remove a payment method, contact Apple Support.

And you have $96 balance ?

Please check -> Check your Apple Account balance

Check your Apple Account balance – Apple Support (UK)

or 

Tap App Store -> tap your Profile (top right of the screen) -> then you will see your Apple Account balance.