How to download the data from encrypted forms?

When using encrypted forms, I can only see the submitted data on the screen. If I download the submission into an excel file, the data is encrypted. 

Unfortunately, this is a limitation of the encrypted forms. The encryption feature was designed to almost make the submission data for viewing purposes only. You cannot have a copy of the decrypted data via email, you cannot download the data as PDF, CSV or Excel as decrypted, same with the other report downloads. You can learn more about this on this guide: https://www.jotform.com/help/344-Encrypted-Forms-and-How-to-Use-Them. Please see the "Important" section on that guide.

I hope that helps.