Guestbook

Hi, I m trying to add this (free) guestbook to my website (writefreely) but I can’t get it with Infuerno’s tip. Can someone help me please!
Source: https://guestbooks.meadowing.club

<script async src="https://guestbooks.meadowing.club/resources/js/embed_script/25/script.js"></script> 
<div id="guestbooks___guestbook-form-container">
    <form id="guestbooks___guestbook-form" action="https://guestbooks.meadowing.club/guestbook/25/submit" method="post">
        <div class="guestbooks___input-container">
            <input placeholder="Name" type="text" id="name" name="name" required>
        </div>
        <div class="guestbooks___input-container">
            <input placeholder="Website (optional)" type="url" id="website" name="website">
        </div>
        <br/>
        <div class="guestbooks___input-container">
            <textarea placeholder="Message..." id="text" name="text" style="width: 100%;" required></textarea>
        </div>
        <br/>
        <input type="submit" value="Submit">
    </form>
</div>
<div id="guestbooks___guestbook-made-with" style="text-align: right;">
    <small>Lovingly made with <a target="_blank" href="https://guestbooks.meadowing.club">Guestbooks</a></small>
</div>  
<hr style="margin: 1em 0;"/>
<h3 id="guestbooks___guestbook-messages-header">Messages</h3>
<div id="guestbooks___guestbook-messages-container"></div>