First issue: I am trying to redirect a page under URL path with UUID parameter to my login page, but it displays “page not found” even though the redirection page exists.
Based on your screenshot, it seems you are creating some sort of infinite loop, redirecting your 404 page (source page) to your 404 page (target page).
There’s no need to create a redirection in this panel unless you want to show the 404 page when the user types in the URL of a page that still exists.
As long as you have created a page in WeWeb with the slug 404, your users will be automatically redirected to that page when they try accessing a page that doesn’t exist.
Does that make sense?
Here are the user docs to create a 404 page in WeWeb: