Order ID missing from submission

hi I am trying to do a practice test with my form and it comes back with order ID is missing from my submission form?? How do I set this up please

Hi,

thank you for reaching out to us. You can add a Unique ID widget to the form. This will create a unique order ID upon each submission.

This should then automatically appear on the submission page and on the notification email.

I hope this helps, please let us know if you need further assistance.