When your account was created for you by a hosting company or another provider, Settings → Billing shows their name, your package and how to reach their support instead of plans and payments. Your plan, invoices and payments are handled by them: ask them to change your package or for help with a bill.
Everything else works the same: the web app, the desktop and mobile apps, sharing and version history, with the storage and features of your package. If your provider gives you a button such as Open Iglubox in their customer area, it signs you in without a password; you can also sign in here with your e-mail address and the password you chose.