Can't get response using REST API in Wordpress

I want to use the Instgram api from RapidApi. This is what RapidAPI shows as the PHP snippet:

<?php

$request = new HttpRequest();
$request->setUrl('https://instagram47.p.rapidapi.com/public_user_posts');
$request->setMethod(HTTP_METH_GET);

$request->setQueryData([
    'userid' => '1718924098'
]);

$request->setHeaders([
    'x-rapidapi-key' => ' ***************** ',
    'x-rapidapi-host' => 'instagram47.p.rapidapi.com'
]);

try {
    $response = $request->send();

    echo $response->getBody();
} catch (HttpException $ex) {
    echo $ex;
}

This is what my code looks like in functions.php:

function get_instaPosts(){
    $request = wp_remote_retrieve_body( wp_remote_get( 'https://instagram47.p.rapidapi.com/user_posts', array(
            'headers' => array(
                "content-type" => "application/json",
                'userid' => '1718924098',
                'x-rapidapi-key' => 'INSTA_APIKEY',
                'x-rapidapi-host' => 'instagram47.p.rapidapi.com'
            ),
            'body' => array()
            )
        ));

    $response_code = wp_remote_retrieve_response_code($response);
    $body = wp_remote_retrieve_body($response);

    if( 401 === $response_code) {
        echo "<pre>";
        print_r("Unauthorised access");
        echo "</pre>";
    }

    if( 200 !== $response_code) {
        echo "<pre>";
        print_r("Error in pinging API");
        echo "</pre>";
    }

    if( 200 === $response_code) {
        echo "<pre>";
        print_r($body);
        echo "</pre>";
    }
}

But its consistently printing the "Error in pinging API" defined in if (200!==...) statement. Printing the $response gives this in between:

[body] => {"message":"Missing required parameters"}

Finally, since they give you a secret API key, is it a good practice to save the actual key as a variable inside wp-config like this and refer it later with just INSTA_APIKEY to not make it public:

/** API key for RapidApi Insta */
define( 'INSTA_APIKEY', '***************' );

FIX: In functions.php:

function get_instaPosts(){
    $userid = ' ** insta userid here ** ';
    $first = '2';
    $after = ' ** the after code here ** ';
    $response = wp_remote_get( "https://instagram40.p.rapidapi.com/account-medias?userid=$userid&first=$first&after=$after", array(
            'headers' => array(
                'x-rapidapi-key' => ' ** secret key ** ',
                'x-rapidapi-host' => 'instagram40.p.rapidapi.com'
                )
            )
        );
        

    $response_code = wp_remote_retrieve_response_code($response);
    $body = wp_remote_retrieve_body($response);
    $decode = json_decode( $body, true );