A Common App ID is issued to every individual who registers an account at commonapp.org. If you don't have an online account, you won't have a Common App ID.
You are welcome to complete your forms by hand and mail them, but you should be aware that every single Common App members prefers that you apply online. What you should NOT do is complete the form online and then print a copy to mail. We can't prevent this, but we discourage it (at the request of the colleges) by printing a big "PREVIEW" watermark across the printed version