The following code will convert the quote to order and will return the order id.
<?php
$magentoURL = "http://127.0.0.1/mage2/";
$apiURL = $magentoURL."index.php/rest/V1/integration/customer/token";
$data = array("username" => "Test.User1521623008@brandmuscle.com", "password" => "Pramod1&");
$data_string = json_encode($data);
$ch = curl_init($apiURL);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: application/json","Content-Length: ".strlen($data_string)));
$token = curl_exec($ch);
$customerData =[
'paymentMethod' => [
"method" => 'quickpay'
],
'billing_address' => [
"region" => 'New York',
"region_id" => "43",
"region_code" => "NY",
"country_id" => "US",
"street" => array("123 Oak Ave"),
"postcode" => "10577",
"city" => "Purchase",
"firstname" => "Pramod",
"lastname" => "Prasad",
"customer_id" => "16",
"email" => "Test.User1521623008@brandmuscle.com",
"telephone" => "(512) 555-1111",
],
];
$requestUrl =$magentoURL.'index.php/rest/V1/carts/mine/payment-information';
$ch = curl_init($requestUrl);
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($customerData));
curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: application/json", "Authorization: Bearer " . json_decode($token)));
$result = json_decode(curl_exec($ch));
echo "<pre>";print_r($result);
?>