Issues with AJAX request to MySQL Database

I am having issues trying to create an AJAX request to the MySQL database hosted within my WordPress site. I have been implementing the PHP needed for the request through the XYZ PHP Snipped plugin, with the block implementing it being placed above my HTML/JS block. My compiled data is in the form of a JSON, as it it a variable amount of tables, which each contain a variable amount of rows. My AJAX request within the JS is as follows:

<script>
var ajaxurl = '/wp-admin/admin-ajax.php';
if (confirm(Are you sure you want to compile the data?\n\n${displayData})) {
        $.ajax({
            type: 'POST',
            url: ajaxurl,
            data: {
                action: 'save_compiled_data',
                compiled_data: JSON.stringify(compiledData)
            },
            success: function(response) {
                alert(response);
            },
            error: function(error) {
                console.error(error);
            }
        });
    }
    })
</script>

And the PHP snippet is as follows:

<?php
function save_compiled_data() {
    global $wpdb;

    // Check if compiled_data is set
    if (!isset($_POST['compiled_data'])) {
        error_log('No data received.');
        wp_send_json_error('No data received.');
        return;
    }

    // Retrieve the compiled data
    $compiled_data = $_POST['compiled_data'];
    error_log('Compiled Data: ' . $compiled_data); // Log the received data

    // Define the table name
    $table_name = $wpdb->prefix . 'compiled_data';

    // Insert the data into the database
    $result = $wpdb->insert(
        $table_name,
        array(
            'data' => maybe_serialize($compiled_data),
            'timestamp' => current_time('mysql')
        )
    );

    // Check for database errors
    if ($result === false) {
        error_log('Database insert failed: ' . $wpdb->last_error); // Log any database error
        wp_send_json_error('Database insert failed: ' . $wpdb->last_error);
    } else {
        wp_send_json_success('Data saved successfully.');
    }
}
add_action('wp_ajax_save_compiled_data', 'save_compiled_data');

Any help would be really appreciated, as I am not particularly experienced with WordPress as a whole.