Show Page number on new Flow

I’ve checked out this video https://blog.dorico.com/2020/10/show-page-numbers-pages-new-flows/ and did exactly what it says, but the page number hasn’t appeared.
Any ideas why that might be?

I think you’re using the First Master Page for the start of each flow. You’d need to add a text frame to the top of the First Master Page, containing the {@page@} token.