Can you please help me to change the default landing when a user tries to access a page that he has no permissions to?

To explain my use case:
I write a newsletter. In the newsletter, I provide links to posts on my website. Some of them are for members only. Like this one: Example post

In my ideal world, a visitor would arrive at a page that says: "Please log in to see this article. If you are not a member yet, please create an account here."

Instead he arrives at this 404-page now (see attachment)...
Can you please teach me how to change this to arrive a step closer to my ideal scenario?

Thank you very much!

Sven