Modal do not want to open - Bootstrap - php

Question

I want to make my modal apper, but I can not to do it.
This is my code:
<div class="container h-100">
<div class="row justify-content-sm-center h-100">
<div class="col-xxl-4 col-xl-5 col-lg-5 col-md-7 col-sm-9">
<div class="text-center my-5">
<img src="img/logo-branca.png" alt="logo" width="100">
</div>
<div class="card shadow-lg">
<div class="card-body p-5">
<h1 class="fs-4 card-title fw-bold mb-4">CEP</h1>
<form method="POST" action = "autenticar.php">
<div class="mb-3">
<input id="cep" type="number" class="form-control" name="cep" value="" required="required">
</div>
<button type="submit" class="btn btn-primary ms-auto">
Pesquisar
</button>
</div>
</form>
</div>
<div class="card-footer py-3 border-0">
<div class="text-center">
<button type="button" class="btn btn-primary" data-bs-toggle="modal" data-bs-target="#staticBackdrop">
BUTTON TO OPEN THE MODAL
</button>
</div>
</div>
</div>
<div class="text-center mt-5 text-muted">
Copyright © 2021 — Rodrigo Franco
</div>
</div>
</div>
</div>
And this my modal:
<div class="modal fade" id="staticBackdrop" data-bs-backdrop="static" data-bs-keyboard="false" tabindex="-1" aria-labelledby="staticBackdropLabel" aria-hidden="true">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<h5 class="modal-title" id="staticBackdropLabel">Modal title</h5>
<button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
</div>
<div class="modal-body">
...
</div>
<div class="modal-footer">
<button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Understood</button>
</div>
</div>
</div>
</div>
If you need to see my project compleatly, just go to this link or if you want to make download the project, just go here

Answer 1

You are not loading Bootstrap's javascript files, simply add:
<script src="https://cdn.jsdelivr.net/npm/bootstrap#5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>
To the head of your document and the modal works.
Resources: https://getbootstrap.com/docs/5.0/components/modal/