Do you need a marketing URL? Because is required for test your app. So can I just make one up that is not real like doesn't open a web or how can I make one that actually opens a page?
Yeah just make a Facebook page or Wordpress or something to promote your app (few screenshots and few words) and put the URL on it. It does not need to be on your own domain name -- although I would suggest doing that so, it is only $10-15 a year and lterally you can just redirect your www.domainname.com to your whatever page you have created. With Google Domain you can just have a free Blogger page and problem solved...