How can I allow respondents edit their own submissions alone?

I have created a form (to populate a contact list) and I want to get 30 of my colleagues (aka Sub-Users) to be able to create entries using this form. I would also like them to have the ability to view and edit their own submissions, but no one else's.  Is this possible? 

Subusers in JotForm are people who either edit forms, view/edit submissions, or both. They don't usually fill out forms. From how you phrased it, your colleagues will be the ones filling out the form. This means they will be the respondents and will not be acting as subusers.

Also, free plan users can only add 1 subuser (max). Each plan will have its own respective number of allowed subusers.

Complete guide: How-to-Share-Forms-with-a-Sub-Account-User

Since your goal is to allow whoever submitted the form to edit their respective submission (and that submission alone), adding the EDIT LINK to the AUTORESPONDER EMAIL that these respondents will receive should suffice.

Complete guide: How-to-Let-Users-Update-Their-Form-Submissions-at-a-Later-Date