Can you add an excel spreadsheet to a form and password protect the file ? Thanks

If you're trying to provide the Excel file to your submitter then you can simply include it in an email auto-responder. 

While you're creating your email auto-responder click on the "Advanced" tab and add your attachment there. 

But do note that this cannot be password protected, it will be send to anyone who submitted your form. 

You may also add the link to your spreadsheet in your form and ask for something to show the field link, but, please avoid using words such as password, passcode, or access code since asking for this info is not allowed at JotForm and your will be suspended. 

This guide will help you to show / hide fields or text based on another field input:How-to-Show-or-Hide-Fields-Base-on-User-s-Answer

Hope this helps.