CDN is not working

I am using trial for my website, I will move from Digitalocean to wpmudev, I configured CDN and even purchased 5$ extra 50GB storage, When I am uploading images to my listing website, the images are not serving on CDN, I saw image url as local. how CDN will work ?

https://flutter.wpmudev.host/listing/honda-city-for-sale-in-good/