To trigger auto-generated IDs to generate en masse on the Enroll Form, you should use the ID# field in the form settings. Follow these steps to set up an auto ID:
Access your Enrollment Form by going to My Company --> Forms --> Enroll Form.
Find the Section you need to add the field to (under Account Info, Enrollee Info, or Program Selection).
After the default fields, click the plus button, and a list of the field elements will appear.
Enter the label name and choose "ID" from the options.
Click Add to add the field
In the Field Settings, switch the toggle at the bottom of the ID# field settings to the "on" position, to enable auto-generated IDs. This will automatically generate unique ID numbers for each enrollment.