When I try to apply to adsense with my URL, https://www.progresscentral.x10.mx, it says: "URL must not have a path (example.com/path) or subdomain (subdomain.example.com). Learn more"
Sorry, I misread the question. It looks like Google AdSense will not allow you to use its service on one of our free hosting sub domains. You could purchase a top-level domain from an external registrar (e.g. .com, .net, .org, etc) to get around this.
I'm afraid not. This is a restriction that Google puts in place, and unfortunately we have no control over this. You would need a top-level domain to be able to use Google AdSense, due to Google's restrictions.