How to get data uploaded to jotform for auto population?

I want to create an unique access code for user to input, once access code entered, some data (e.g. their contacts) will be auto populated, and how to get data uploaded to jotform for auto population?

Hello,

It seems that the Spreadsheet to Form widget will meet your requirements.  The Spreadsheet to Form widget allows you to upload your spreadsheet to your form and use the values you have on the spreadsheet to pre-populate your form.  Please refer to this detailed guide: How-to-use-the-spreadsheet-to-form-widget

For reference: How-to-add-a-widget-to-your-form

I hope this helps. Let us know if you need further assistance.