I urgently need to create a page with forms. I want to use conditional input areas.
Feature #1: The submit button works only if the input matches with any of the predefined values. I will provide invitation codes to some people by email. (I will do this manually.) So I want only the users with an invitation code to be able to submit forms. Also, each code can be used for a single time only. I want to prevent anybody without an invitation code to submit the signup form to our beta program even though the link of the signup page is shared with any third person.
Feature #2: There are some usernames which are taken before. So I want to prevent new appliers to get that names and let them know the name they type is already taken.
Feature #3: A valid email address has to be typed. (I mean in the valid format like "firstname.lastname@example.org"
How can I do such a thing? I have a Webflow plan but if it is not directly possible in Webflow, I can use anything available with it.