error – the page cannot be found

hello, i installed the plugin but, then i accessed the file in the incognito mode, when to the comments section, clicked “You can also subscribe without commenting.” and it took me to an empty page with the text:
“Oops! Page not found.
Sorry but the page you looking for cannot be found.

Better to go home”

same happens when i’m logged in as admin and click on “You can manage the subscriptions of this post.”
what is the problem?

https://wordpress.org/plugins/subscribe-to-comments-reloaded/