newbie hook question

Hello, I want to use a product for a plugin customization shop. There is a template error, I want to know where I have to add the recommended code :
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woocommerce_before_add_to_cart_button hook is missing in the woocommerce templates of your theme. Help me fixing it.

They ask me :
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Missing hook: woocommerce_before_add_to_cart_button

The add-to-cart templates does not include the required :

do_action( ‘woocommerce_before_add_to_cart_button’ );

Check out the standard templates in “plugins/woocommerce/templates/single-product/add-to-cart/”, to see how it is supposed to look.

<td class=”product-thumbnail”>
    <?php
        $thumbnail = apply_filters( ‘woocommerce_cart_item_thumbnail’, $_product->get_image(), $cart_item, $cart_item_key );
 
        if ( ! $_product->is_visible() )
            echo $thumbnail;
        else
            printf( ‘%s‘, $_product->get_permalink(), $thumbnail );
    ?>
</td>

+++++++++++++++++++++++

So I check this file :

plugins/woocommerce/templates/single-product/add-to-cart

Inside I have :

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?>

<?php if ( $product->is_in_stock() ) : ?>

<?php do_action( ‘woocommerce_before_add_to_cart_form’ ); ?>

<form class=”cart” method=”post” enctype=’multipart/form-data’>
<?php do_action( ‘woocommerce_before_add_to_cart_button’ ); ?>

<?php
if ( ! $product->is_sold_individually() ) {
woocommerce_quantity_input( array(
‘min_value’ => apply_filters( ‘woocommerce_quantity_input_min’, 1, $product ),
‘max_value’ => apply_filters( ‘woocommerce_quantity_input_max’, $product->backorders_allowed() ? ” : $product->get_stock_quantity(), $product ),
‘input_value’ => ( isset( $_POST[‘quantity’] ) ? wc_stock_amount( $_POST[‘quantity’] ) : 1 )
) );
}
?>

<input type=”hidden” name=”add-to-cart” value=”<?php echo esc_attr( $product->id ); ?>” />

<button type=”submit” class=”single_add_to_cart_button button alt”><?php echo esc_html( $product->single_add_to_cart_text() ); ?></button>

<?php do_action( ‘woocommerce_after_add_to_cart_button’ ); ?>
</form>

<?php do_action( ‘woocommerce_after_add_to_cart_form’ ); ?>

<?php endif; ?>

++++++++++++++++++++++++++++++++++

So where am I supposed to add the missing lines ?

Thanks.