installation by copy/paste js file without composer
Add the following code to the file view (e.g _form.php)
$this->registerJsFile('@web/js/ckeditor/ckeditor.js');
<?= $form->field($model, 'description')->textarea(['class' => 'ckeditor']) ?>Configuration is file /js/ckeditor/config.js
Configuration upload file (kcfinder)
Configuration is file /js/ckeditor/kcfinder/config.php