The 20 GB for $20 Data Plus option is only available on the $28 /mo Base Plan and $65 /mo +Phone Plan.
Step 1: Go to www.circles.life and create a account or login into your account.
Step 2: When building your Base Plan, just select the 20 GB for $20 Plus option as show below.
Step 3: Complete the checkout process and voilà, it’s added to your mobile subscription! You’ll be able to enjoy it right away when you receive you SIM Card!