Hi mate,
If you named your form as "login_form", I assume you are seeing the name as output on your browser network tab under "login_form"?
If so, in your front-end, for a paragraph, the data picker should show "login_form", and under that you should see the output to bind it. It will look like this:
{{login_form.data.name}}
You are not alone, I was initially lost too, see this old thread - Form submit, use the linked server action's output on form success event - #2 by Teodor