How to send notifications on new blog post

Hi

I noticed that ever since I signed up with WPMUDEV, whenever WPMUDEV publish a new blog post, there will be a rectangular notification that slides in on the top right corner of my desktop screen, notifying me on the new WPMUDEV blog post. Can you advise how such notification is done? I would like to implement such notifications to inform my users/subscribers who have made purchases or signed up on my Multisite Wordpress website to also be notified whenever I publish a new blog post. Can you advise if there are plugins to achieve such notifications? What are the steps to take to achieve that? Also, how can I style the notifications? The WPMUDEV notification is well styled with blog title and image.

Looking forward to your advise.

Thank you.

Esther