Pass the GET URL parameter to server action step via $GET.key

Thanks for chipping in.
The GET.key url param is a uuid for registering behind a protected page. UUID is verified against those recorded in the database (DB). If they match, the registration page opens up.

That page has a standard form with input fields that are saved to our DB via API.


During form submission, we want to save the newly registered userID who used that uuid.
Right now we’re using the POST method with the key in hidden input field.
But I’d rather have that key on the server side from a $GET.key variable since the key is in the URL. But that $GET.key is empty, even when defined in Globals. Any clue why?

Can’t seem to get this method Filtering Database Query with an URL Parameter to work.