Rss problem with davidjeddy\RssFeed\RssReader

I set up davidjeddy\RssFeed\RssReader at my project with composer,I see the code at vendor folder but there is the error at my view Class ‘davidjeddy\RssFeed\RssReader’ not found.
I follow the instructions from here
https://packagist.org/packages/davidjeddy/yii2-rss-reader
this is the code,What is wrong?

echo davidjeddy\RssFeed\RssReader::widget([
‘channel’ => ‘https://www.newsbeast.gr/greece/feed’,
‘itemView’ => ‘item’,
‘pageSize’ => 5,
‘wrapClass’ => ‘rss-wrap’,
‘wrapTag’ => ‘div’,
]);

Maybe the app can not load this class,What may be wrong.
I used this code
https://www.the-art-of-web.com/php/rss/