Checkbox fields at student registration

Hello,

I want to add checkbox field in Student Registration page, for Terms & Conditions..and it should also be Validation..i have done but validation part is not working, see below code..

Below i have added code in student registration page

<div class="tutor-form-row" style="padding-top:20px;">
            <div class="tutor-form-col-12">
                <div class="tutor-form-group">
				<label>
                        <?php _e('Terms & Conditions', 'tutor'); ?>
                    </label>
                    <input type="checkbox" name="terms_n_policy" <?php if(isset($_POST['terms_n_policy'])) echo 'checked="checked"'; ?>>  I agree to YogiImpressions Life Academy's <a href="terms-conditions/" target="_blank">Terms of Use</a> & <a href="/privacy-policy/" target="_blank">Privacy Policy</a>.
                </div>
            </div>
        </div>

And below code i have added in functions.php page

add_action( 'user_register', 'bt_add_checkout_checkbox_warning' );
/**
 * Alert if checkbox not checked
 */ 
function bt_add_checkout_checkbox_warning() {
    if ( ! (int) isset( $_POST['terms_n_policy'] ) ) {
        wc_add_notice( __( 'Please acknowledge the Checkbox' ), 'error' );
    }
}

but above code is not working for checkbox validation….

regards
Prakash