Issue with Web APIAnswered

I would like to add a form on the website that can be activated offline. I added two php files to the page (in attachments) - everything seems to work, but it returns wrong XML - on website https://auroradsp.com/activate. The case seems simple (we didn't change anything in the code except adding an API and a php connection) - what else needs to be done to make it work. We want to share this solution with people without logging in on our eshop or your limeLM website.