Add list of items to standard button for payment

[Geno21]

Feels like it should be possible to create an order with multiple items using standard buttons generated on the Paypal site. Clearly I'm missing something and would appreciate any assistance or information. Below is my page source code and the error message received when pressing the Pay button.

<div id="paypal-button-container"></div>
<!-- Include the PayPal JavaScript SDK -->
<script src="https://www.paypal.com/sdk/js?client-id=MY_SANDBOX_CLIENT_ID&enable-funding=venmo&currency=USD&debug..."></script>
<script>
// Render the PayPal button into #paypal-button-container
paypal.Buttons({
style: {
color: 'blue',
shape: 'rect',
label: 'pay',
},

// Sets up the transaction when a payment button is clicked
createOrder: function(data, actions) {
return actions.order.create({
intent: 'CAPTURE', //capture payment from buyer
payer: {
name: {
given_name: "John",
surname: "Doe"
},
address: {
address_line_1: "<removed>",
address_line_2: "Apt 2",
admin_area_2: "Sacramento",
admin_area_1: "CA",
postal_code: "<removed>",
country_code: "US"
},
email_address: "sb_test_email_address",
phone: {
phone_type: "MOBILE",
phone_number: {
national_number[Removed. Phone #s not permitted]
}
}
},

purchase_units: [{
description: "My Purchases",
amount: {
currency_code: "USD",
value: "12.00", // Purchase Total
breakdown: {
item_total: {
currency_code: 'USD',
value: "12.00",
},
shipping: {
currency_code: 'USD',
value: "0",
},
tax_total: {
currency_code: 'USD',
value: "0",
}
}
},
items: [{
name: "Item 1",
unit_amount: {
currency_code: 'USD',
value: "6.00",
},
quantity: "1",
name: "Item 2",
unit_amount: {
currency_code: 'USD',
value: "6.00",
},
quantity: "1"
}]
}]
});
},

// Finalize the transaction after payer approval
onApprove: function(data, actions) {
return actions.order.capture().then(function(orderData) {
window.location.href = "Thanks.html";
});
},

onCancel: function(data) {
//payment cancelled
alert("Payment Cancelled");
},

onError: function(err) {
alert("Error Message: " + err);
}
}).render('#paypal-button-container');
</script>
</div>