How do you buy Robux with a gift card?

How do you buy Robux with a gift card?
From the Membership or Robux purchase pages

Log into the Roblox account where you redeemed the gift card on the browser.
Go to the membership purchase page or the Robux purchase page.
Select the product you want to purchase.
Select Roblox Credit as the payment type and click Continue.
Click Submit Order.

From the Membership or Robux purchase pages
  1. Log into the Roblox account where you redeemed the gift card on the browser.
  2. Go to the membership purchase page or the Robux purchase page.
  3. Select the product you want to purchase.
  4. Select Roblox Credit as the payment type and click Continue.
  5. Click Submit Order.