I am trying to achieve my Client Requirement Here. There is a Field Citizen ID in the Zoho Lead Module. Can I create a function where-in I can validate the Citizen ID in the Form with CRM?For example like Indian Aadhar Number. If a Person already submitted the form previously with the same Aadhar Number, he should not submit the form again. and if he does the form should not let him submit and should show him an Error like " You already submitted the Form using the same Aadhar ID"
So Before Submitting the Form, the Form should Validate the Citizen ID # from the CRM Leads Module, and If it is already present There should not allow the user to click Submit and it should show the above Error. I read something like we can use an Ajax Query for this but seems like there is a limitation for subscription due to security concerns.

Please assist me with this.