You can either use the Auth then Void mode (2 requests),
Or you can directly send a Register mode request which do the same (Auth then Void) in one request.

Sample:
{
    "profile_id": {{profile_id}},
    "tran_type": "register",
    "tran_class": "ecom",
    "cart_id": "cart_11111",
    "cart_currency": "{{currency}}",
    "cart_amount": 12.3,
    "cart_description": "Description of the items/services",
    "paypage_lang": "en",
    "customer_details": {
        "name": "wajih last",
        "email": "[email protected]",
        "phone": "0522222222",
        "street1": "address street",
        "city": "dubai",
        "state": "du",
        "country": "AE",
        "zip": "12345"
    },
    "hide_shipping": true,
    "callback": "{{callback_url}}",
    "return": "{{return_url}}"
}


The generated payment page: (Note the Pay button - Verify Card)