Are you downloading Sphere for the first time?
Please follow this link https://www.sphereapp.fr/signup to create an account.
Once your account is created you'll receive an email to validate it. You can then access a reserved part of the site, your personal page, on https://www.sphereapp.fr/#login_zone
There you can find the permalink to download Sphere.
Once you've downloaded it, you won't need to come back to this page again, as it will automatically update.