Problem with Permalinks Custom Structure Category base

Hello,

I’m creating a website and we will have a blog in this url

https://www.mysite.com/blog

I want the URL of my blog entries like this

https://www.mysite.com/blog/entry-title

I want the word “blog” before the entry title

I am setting up the permalinks to use Custom Structure / Category it doesn’t work.

These are the options I selected, see image here

Can somebody tell me if I did something wrong and how to fix it?

Thank you in advance!